Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “differential expression”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources
PubMed2003

Differentially expressed genes and estrogen receptor status in breast cancer.

There is a large and increasing body of experimental and clinical data supporting the involvement of estrogen on the proliferation of hormone-dependent breast tumors. Estrogen acts via its receptor (ER) stimulating cellular proliferation. ER and progesterone receptor (PR), which is regulated by estrogen via ER, have been used as prognostic markers in the clinical management of breast cancer patients. The aim of the present study was the identification of tumor-associated genes differentially expressed in breast tumors regarding the presence or absence of ER and PR. Using the technique of differential display reverse transcriptase-polymerase chain reaction (DDRT-PCR) we have isolated and cloned 127 cDNA fragments that showed differential expression in either ER+/PR+ or ER-/PR- breast tumors. Sequencing analysis of these clones revealed that 119 cDNAs had homology with known sequences in the National Center of Biotechnology Information (NCBI) and 8 were novel, showing no homology to known genes. Among these differentially expressed transcripts are metabolic enzymes, ribosomal proteins, transcription factors, hypothetical proteins, cell cycle regulators, cytoskelectum related genes, cell adhesion and motility genes. Differences in gene expression profiles are likely to explain the phenotypic differences between hormone-responsive and hormone-unresponsive breast tumors.

Breast Neoplasms↗
PubMed2001

Detection of differentially expressed genes in the early developmental stage of the mouse mandible.

We previously examined the development of the mouse mandible, and demonstrated that odontogenesis occurs between embryonic day 10.5 (E10.5) and E12. Based on the histological findings, we performed cDNA subtraction between the E10.5 and E12 mandibles to detect any differentially expressed genes which might be involved in the initiation of odontogenesis. By sequencing, homology search and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), we thus found Pgk-1, Ccte, Hsp86, Nucleolin, Hsc73, Frg1, N-ras, Set alpha and Hsj2 from the E10.5 mandible, and E25, ATPase6, Mum2, Thymosin beta4 and L21 from the E12 mandible to be differentially expressed genes. These genes are functionally related to protein transport, signal transduction, transcription, translation and molecular chaperon activity. In situ hybridization analyses of Set alpha and E25 showed that Set alpha was detected in the tooth germ at E12 and E14.5, thus indicating a close relationship of this gene to odontogenesis. Meanwhile, the in situ signal of E25 was found in the muscular layer of the tongue, thus suggesting E25 to be related to the differentiation of muscular tissue. In conclusion, we found 15 differentially expressed genes in the course of the early developmental stage of the mouse mandible using a combination of the cDNA subtraction and semi-quantitative RT-PCR methods, while in addition, two genes were demonstrated to be related to the initiation and the development of both tooth germ and the tongue according to the in situ hybridization technique.

Animals↗
PubMed1975

Differential expression of alpha- and beta-globin genes during differentiation of cultured erythroleukemic cells.

Murine erythroleukemic cells induced to differentiate in vitro with dimethylsulfoxide provide a model for events involved in the regulated expression of the globin genes. Here we examine alpha- and beta-globin gene expression in such cells which contain no detectable globin RNA prior to induction. To quantitate alpha- and beta-globin RNAs in cellular RNA samples by molecular hybridization techniques, highly radioactive complementary DNAs were synthesized using mouse alpha- and beta-globin RNAs purified by formamide gel electrophoresis. Maximally induced erythroleukemic cells and mouse reticulocytes contain nearly equal relative amounts of alpha- and beta-globin RNA. During the period in which globin RNA accumulates in differentiating erythroleukemic cells, however, alpha- and beta-globin RNAs are not present in equivalent amounts. alphaRNA is present in substantial excess (alpha/beta ratio 3.7) early in induction, and the alpha/beta RNA ratio progressively approaches 1 as differentiation proceeds further. These observations directly suggest that the alpha- and beta-globin genes are differentially expressed during cellular differentiation and raise questions as to how relative expression of globin genes is controlled during normal development.

Animals↗
PubMed2005

Interleukin-32, CCL2, PF4F1 and GFD10 are the only cytokine/chemokine genes differentially expressed by in vitro cultured rheumatoid and osteoarthritis fibroblast-like synoviocytes.

Since cytokines and chemokines are important actors in rheumatoid arthritis (RA), the aim of this study was to compare the gene expression profiles in cultured fibroblast-like synoviocytes (FLS) obtained from patients with either RA, or osteoarthritis (OA), focusing our analysis on genes for cytokines and chemokines, and their respective receptors. Gene expression in cultured FLS (third passage) from eight patients with RA (RA-FLS) were compared with gene expression in cultured FLS from nine patients with OA (OA-FLS) using Affymetrix Human Genome U133 Plus 2.0 Array microarray, allowing analysis of over 54,000 transcripts. Among the 171 genes studied (241 probes), limiting the selection of differentially expressed genes to a significant value (p < 0.05), and a differential ratio of expression > 1.6, only four genes, namely IL-32, CCL2, PF4F1 and GDF10 were found to be differentially expressed. Out of these four genes, only higher expression of CCL2 has been reported previously in RA. The newly described cytokine IL-32 was the most prominently differentially expressed gene in the present study, with higher expression in RA-FLS than in OA-FLS (p < 0.0073). IL-32 might have a previously unidentified pivotal role in RA.

Arthritis, Rheumatoid↗
PubMed1998

Alpha, beta, and gamma mineralocorticoid receptor messenger ribonucleic acid splice variants: differential expression and rapid regulation in the developing hippocampus.

Two different types of corticoid receptor molecules bind circulating corticosterone in brain: mineralocorticoid receptors (MR) and glucocorticoid receptors. MR exhibit the highest affinity for the endogenous glucocorticoid in the rat, corticosterone. During development, low corticosterone levels influence neurogenesis, and these effects are probably MR mediated. Three MR complementary DNA clones, alpha, beta, and gamma, have been identified in the rodent. All of these MR complementary DNA clones have identical coding regions, but differ significantly at the 5'-untranslated end. Although the functional significance of these three messenger RNA (mRNA) species remains unknown, one hypothesis is that they reflect the ability of the brain to regulate the expression of MR, allowing multiple factors to differentially control transcription in a tissue- and time-specific manner. To investigate this possibility, we examined the presence of these distinct mRNA forms in the developing rat hippocampus (HC). In situ hybridization with specific alpha, beta, and gamma complementary RNA probes was performed in the HC of 3-, 5-, 7-, 12-, 14-, 28-, 35-, and 65-day-old animals. We found that there is differential expression of these forms in each of the HC subfields from infancy to adulthood. y expression appears to be associated with periods of cell birth and increased axonal sprouting. beta expression, on the other hand, may be best linked to periods of synaptogenesis, growth of commissural and associative terminal fields, and possibly active pruning. To explore the possibility that the differential gene expression may be related to corticosterone environment, adrenalectomy was performed. A rapid modulation of the MR mRNA variants (14 h) in an age- and site-specific fashion was seen. These findings suggest that the variation in expression and regulation during development of the multiple MR transcripts could reflect a complex pattern of developmental regulation that may involve a multitude of factors unique to each postnatal age and to the different neuronal populations within the hippocampal formation.

Adrenalectomy↗
PubMed2003

The pattern of differentially expressed genes in biliary atresia.

Biliary atresia is a progressive obliterative cholangiopathy, but the etiology of this disorder remains uncertain. Identifying genes specifically expressed in biliary atresia and analyzing the pattern of expression may lead to a better understanding of the pathogenesis. Liver tissues were taken from a recipient with biliary atresia and a normal donor during liver transplantation. Total RNA was extracted from each sample and reversely transcribed to cDNA. Then radiolabeled cDNA probe pools were made by random primed DNA labeling method and used for screening of differentially expressed genes by hybridizing with expressed sequence tags (EST) dot blot panel. Northern blot hybridization was done to confirm that these genes are also differentially expressed in other liver tissues. Among 1730 EST clones, 26 cDNA clones were significantly overexpressed in biliary cirrhosis, while 2 clones were significantly decreased in biliary atresia. By Northern blot hybridization, the results of tissue inhibitor of metalloproteinase (TIMP)-1 and IGFBP-2 were well correlated with differential EST screening (DES). This study identified the pattern of differentially expressed genes in the biliary cirrhosis due to biliary atresia using DES technique.

Biliary Atresia↗
PubMed1993

Alpha 4 beta 1 and alpha 5 beta 1 are differentially expressed during myelopoiesis and mediate the adherence of human CD34+ cells to fibronectin in an activation-dependent way.

To study the receptors involved in the interaction between extracellular matrix proteins and hematopoietic progenitor cells, we analyzed the expression of beta 1 integrins on CD34+ bone marrow cells by means of immunoflowcytometry. Alpha 4 beta 1 and alpha 5 beta 1 were expressed, whereas alpha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 1, and alpha v beta 1 were virtually absent. Furthermore, we assessed the alpha 4 and alpha 5 expression on committed myeloid progenitor cells. These colony-forming cells were detected in the alpha 4 dull fraction and the alpha 5 dull fraction. During myeloid differentiation, both in vivo and in vitro, a differential expression of alpha 4 beta 1 and alpha 5 beta 1 was observed. alpha 5 beta 1 was found to be lost at the myelocytic-metamyelocytic stage, before the loss of alpha 4 beta 1, at the band stage. Functional studies showed no binding of erythroid progenitor-depleted, CD34+ bone marrow cells to fibronectin. However, protein kinase C activation strongly induced fibronectin binding (68% of the cells). Inhibition experiments with specific antibodies and peptides showed the binding to be mediated by both alpha 4 beta 1 and alpha 5 beta 1. Also, colony-forming cells of granulocytes and macrophages were demonstrated to adhere to fibronectin in an activation-dependent way. During granulocyte colony-stimulating factor-induced in vitro maturation, the activation-dependent fibronectin binding capacity is gradually lost. We conclude that: (1) CD34+ bone marrow cells express alpha 4 beta 1 and alpha 5 beta 1; (2) the expression of alpha 4 beta 1 and alpha 5 beta 1 is differentially expressed during myeloid differentiation; and (3) binding of CD34+ bone marrow cells to fibronectin is activation dependent.

Antibodies, Monoclonal↗
PubMed2003

Serine protease inhibitor-E2 (SERPINE2) is differentially expressed in granulosa cells of dominant follicle in cattle.

The objective was to analyze gene expression in bovine granulosa cells of the dominant follicle by mRNA differential display. Total RNA was extracted from granulosa cells of <or=4 mm follicles, day 5 (D5) dominant follicles, and hCG-induced preovulatory follicles. A differentially expressed cDNA observed in the dominant follicle group was used to screen a granulosa cell cDNA library, which resulted in the cloning of a 2,096 bp cDNA. Amino acid comparison showed identity level of 91.4, 83.9, and 83.1% when compared to human, rat, and mouse serine protease inhibitor E2, SERPINE2, also called Glia-derived nexin or protease Nexin-1. A single transcript of 2.4 kb was shown to be differentially expressed in different bovine tissues. Immunoblotting with a specific antibody raised against a fragment of SERPINE2 (S(12)-R(196)) showed that SERPINE2 migrated at 47.5 kDa in support of glycosylation. Primordial, primary, and secondary pre-antral follicles showed immunostaining associated with granulosa cells and oocytes, and strong labeling in large antral follicles was located with granulosa cells and follicular fluid. Heterogeneity of SERPINE2 labeling was observed in CL. Semi-quantitative real-time fluorescent RT-PCR showed a six-fold increase (P = 0.0002) in mRNA level of SERPINE2 in granulosa cells of D5 dominant follicle compared to granulosa cells collected from the <or=4 mm or preovulatory hCG-induced follicles. This report demonstrates that SERPINE2 mRNA is regulated in a spatio-temporal pattern with highest levels in granulosa cells of growing dominant bovine follicles, and support the hypothesis that a high expression of SERPINE2 may contribute to follicular growth whereas a decrease following hCG injection may contribute to ovulation.

Amino Acid Sequence↗
PubMed2005

Differential expression of a V-type ATPase C subunit gene, Atp6v1c2, during culture of rat lung type II pneumocytes.

The lung alveolar epithelium consists of type I and type II pneumocytes. In vivo, the type II cell is the progenitor cell from which the type I cell originates. When freshly-isolated type II cells are cultured under conventional conditions they rapidly lose their phenotypic properties and attain characteristics of type I cells. Taking advantage of this transdifferentiation, we sought to identify genes that are differentially expressed during culture of rat type II cells. Using suppression subtractive hybridization (SSH), a vacuolar-type H+-ATPase (V-ATPase) C2 subunit gene (Atp6v1c2) was found to be enriched in freshly isolated rat type II cells compared to those cultured for 4 days. Northern blotting and reverse-transcription polymerase chain reaction (RT-PCR) confirmed the differential expression of Atp6v1c2 during in vitro culture of isolated type II cells. Expression ofAtp6v1c2 was significantly reduced early during in vitro culture: almost 90% reduction was observed after 24 h of incubation as determined by real-time PCR. In situ hybridization showed that Atp6v1c2 is expressed in both bronchiolar and alveolar lung epithelial cells, an expression pattern similar to that of surfactant protein B (SP-B). Multi-tissue Northern blotting revealed a unique tissue distribution with Atp6v1c2 expression limited to lung, kidney and testis. The presence and expression of Atp6v1c2 gene transcript isoforms, resulting from alternative splicing, were also investigated. Elucidation of differential expression of Atp6v1c2 in type II cells and further studies of its regulation may provide information useful in understanding the molecular mechanism underlying phenotypic and functional changes during transdifferentiation of alveolar epithelial cells.

Alternative Splicing↗
PubMed2005

Differential expression of protease activated receptor 1 (Par1) and pY397FAK in benign and malignant human ovarian tissue samples.

Protease activated receptors (PAR) form a family of G-protein coupled receptors (GPCR) encoding their own ligands and uniquely activated via proteolytic cleavage. Although proteases in general have been implicated in the remodeling of the extracellular tumor microenvironment, the role of cell surface receptors activated by proteolysis is now emerging. In our present study we investigated the expression pattern of protease activated receptor 1 hPar1 in ovarian carcinoma tissue samples. Abundant hPar1 mRNA and protein were detected in "low malignant potential" and in invasive carcinomas, regardless of the histological subtype. In contrast, no hPar1 expression was detected on the cell surface of normal ovarian epithelium. The differential expression pattern of hPar1 was shown by in situ hybridization, immunohistochemistry and semi-quantitative RT-PCR analyses. In early stages of ovarian carcinoma (Ia), the contra lateral normal ovary showed strong PAR1 expression as opposed to the lack of expression in the ovarian epithelium obtained from normal individuals. In parallel, we analyzed the expression pattern of alphavbeta5 integrin and of activated focal adhesion kinase (FAK), a major focal contact protein, in these tissues. Although abundant expression of alphavbeta5 integrin was observed in all tissues specimens examined, regardless of either normal or malignant, the level of activated FAK was differentially expressed. Phosphorylated FAK was seen in invasive ovarian carcinoma, but not in the normal ovarian epithelium. The abundant hPar1 levels in pathological malignant ovarian carcinoma is likely to transmit signals leading to the phosphorylation of FAK and thereby alterations in the integrin functional state. Altogether our data suggest that hPar1 and FAK cooperate to promote ovarian cancer malignancy.

Adenocarcinoma, Clear Cell↗
PubMed2002

Identification of differentially expressed genes induced by transient ischemic stroke.

We have used a rat model of focal cerebral ischemia to investigate changes in gene expression that occur during stroke. To monitor these changes, we employed representational difference analysis-polymerase chain reaction (PCR). A total of 128 unique gene fragments were isolated, and we selected 13 of these for quantitative reverse transcriptase-PCR analysis. Of these 13 genes, we found seven that were differentially expressed. Four of these genes have not previously been implicated in stroke, and include neuronal activity regulated pentraxin (Narp), cysteine rich protein 61 (Cyr61), Bcl-2 binding protein BIS (Bcl-2-interacting death suppressor), and lectin-like ox-LDL receptor (LOX-1). We demonstrated differential expression of each gene by quantitative PCR analysis, and in the case of LOX-1, we further confirmed differential expression by in situ hybridization. LOX-1 expression is induced greater than ten fold at the core lesion site, and is essentially localized to the ipsilateral half of the brain. LOX-1 appears to be expressed in a non-neuronal cell type, and it does not appear to be expressed in vascular endothelial cells within the brain. This suggests that LOX-1 may serve a novel function in the brain.

Animals↗
PubMed2000

Large-scale identification of differentially expressed genes during neurogenesis.

We report here a modified mRNA differential display method and its application for the analysis of differential gene expression in NGF-treated PC12 cells and in embryonic rat spinal cord. The optimized protocol is based on low fidelity priming of multiple cDNAs followed by high fidelity amplification. In PC12 cells induction by nerve growth factor (NGF) altered the expression of 4% of the 466 transcripts evaluated. During neurogenesis of the spinal cord we found that 30% of the 288 examined products changed. The differential expression of the characterized genes was confirmed by independent quantitative PCR. We conclude this method is suitable for the identification of increases and decreases of mRNA levels and allows the discovery of differentially expressed unknown transcripts.

Animals↗
PubMed1996

Ontogeny of pituitary transcription factor-1 (Pit-1), growth hormone (GH) and prolactin (PRL) mRNA levels in male and female rats and the differential expression of Pit-1 in lactotrophs and somatotrophs.

Pituitary transcription factor-1 (Pit-1 or GHF-1), a transcription factor specific to the anterior pituitary, is involved in the expression and regulation of the growth hormone (GH) and prolactin (PRL) genes. Post-pubertally, the expression of both GH and PRL becomes sexually dimorphic with males having higher GH levels and females higher PRL levels; however, little is known about the postnatal regulation of their common transcription factor. Furthermore, whether the Pit-1 gene is differentially expressed in somatotrophs and lactotrophs remains to be elucidated. In this study, we used in situ hybridization histochemistry to examine Pit-1, GH and PRL mRNA levels in the anterior pituitaries of male and female rats throughout development (0, 5, 10, 20, 30, 40 and 60 days of age) to determine when GH and PRL production becomes sexually dimorphic and if this is accompanied by a dimorphism in Pit-1 gene expression. In addition, the level of Pit-1 mRNA was determined separately in both GH mRNA and PRL mRNA containing cells during the various developmental stages. We found that in both males and females the mRNA levels of Pit-1, GH and PRL remain relatively unchanged until around the time of pubertal onset (30-40 days) when there is a significant increase in all three mRNA species, which is followed by a decrease to adult levels. Also around the time of puberty, both GH and PRL mRNA levels become sexually dimorphic, with males having higher levels of GH mRNA and females higher PRL mRNA levels. In contrast, at no time during development were overall Pit-1 mRNA levels found to differ between the sexes. However, when Pit-1 mRNA content was measured separately in specific cell types, significant differences between the sexes became evident. Throughout development Pit-1 mRNA levels are higher in lactotrophs of females than in those of males, whereas in somatotrophs males have higher Pit-1 mRNA levels than females. Furthermore, within a sex there is differential expression of Pit-1 in the two cell types with females having significantly higher levels of Pit-1 in lactotrophs than in somatotrophs and males having higher levels in somatotrophs than in lactotrophs. These data support the hypothesis that a sexual dimorphism exists in the expression and pituitary specific transcription factor Pit-1; however, this dimorphism is not manifest as a difference in overall mRNA levels, but in the differential expression of this gene in lactotrophs and somatotrophs.

Aging↗
PubMed2005

A theoretical analysis of the selection of differentially expressed genes.

A great deal of recent research has focused on the challenging task of selecting differentially expressed genes from microarray data ("gene selection"). Numerous gene selection algorithms have been proposed in the literature, but it is often unclear exactly how these algorithms respond to conditions like small sample sizes or differing variances. Choosing an appropriate algorithm can therefore be difficult in many cases. In this paper we propose a theoretical analysis of gene selection, in which the probability of successfully selecting differentially expressed genes, using a given ranking function, is explicitly calculated in terms of population parameters. The theory developed is applicable to any ranking function which has a known sampling distribution, or one which can be approximated analytically. In contrast to methods based on simulation, the approach presented here is computationally efficient and can be used to examine the behavior of gene selection algorithms under a wide variety of conditions, even when the number of genes involved runs into the tens of thousands. The utility of our approach is illustrated by comparing three widely-used gene selection methods.

Algorithms↗
PubMed1999

A recombinase-based selection of differentially expressed bacterial genes.

Bacterial genes are often differentially expressed in response to specific environmental conditions. We have devised a method to identify regulated bacterial promoters, such that transient promoter expression leads to a permanent and selectable change in bacterial phenotype. This system consists of a promoterless derivative of cre, the phage P1 recombinase, carried on a plasmid, and two chromosomal loxP sites, the targets of the Cre recombinase. The loxP sites flank npt, conferring kanamycin resistance, and sacB, which confers sensitivity to sucrose, allowing positive selection for both the presence and absence of this chromosomal cassette. Fusion of active promoters to cre induces recombination of the loxP sites and deletion of intervening DNA, allowing selection on media containing sucrose, while inactive promoters fail to induce recombination and so remain resistant to kanamycin. We tested the system in Salmonella typhimurium using a known regulated promoter, that from the araBAD operon, and found it to be a sensitive indicator of gene expression over a wide range of promoter induction. We then used this system to identify S. typhimurium genes that are specifically expressed when bacteria interact with cultured epithelial cells and identified a novel DNA fragment, not found in E. coli, which might represent part of a new pathogenicity island.

DNA, Bacterial↗
PubMed2005

A practical false discovery rate approach to identifying patterns of differential expression in microarray data.

SUMMARY: Searching for differentially expressed genes is one of the most common applications for microarrays, yet statistically there are difficult hurdles to achieving adequate rigor and practicality. False discovery rate (FDR) approaches have become relatively standard; however, how to define and control the FDR has been hotly debated. Permutation estimation approaches such as SAM and PaGE can be effective; however, they leave much room for improvement. We pursue the permutation estimation method and describe a convenient definition for the FDR that can be estimated in a straightforward manner. We then discuss issues regarding the choice of statistic and data transformation. It is impossible to optimize the power of any statistic for thousands of genes simultaneously, and we look at the practical consequences of this. For example, the log transform can both help and hurt at the same time, depending on the gene. We examine issues surrounding the SAM 'fudge factor' parameter, and how to handle these issues by optimizing with respect to power.

Algorithms↗
PubMed2006

OpWise: operons aid the identification of differentially expressed genes in bacterial microarray experiments.

BACKGROUND: Differentially expressed genes are typically identified by analyzing the variation between replicate measurements. These procedures implicitly assume that there are no systematic errors in the data even though several sources of systematic error are known. RESULTS: OpWise estimates the amount of systematic error in bacterial microarray data by assuming that genes in the same operon have matching expression patterns. OpWise then performs a Bayesian analysis of a linear model to estimate significance. In simulations, OpWise corrects for systematic error and is robust to deviations from its assumptions. In several bacterial data sets, significant amounts of systematic error are present, and replicate-based approaches overstate the confidence of the changers dramatically, while OpWise does not. Finally, OpWise can identify additional changers by assigning genes higher confidence if they are consistent with other genes in the same operon. CONCLUSION: Although microarray data can contain large amounts of systematic error, operons provide an external standard and allow for reasonable estimates of significance. OpWise is available at http://microbesonline.org/OpWise.

Algorithms↗
PubMed2005

Modified representational difference analysis: isolation of differentially expressed mRNAs from rare cell populations.

Representational difference analysis of cDNAs (cDNA-RDA) is a sensitive subtractive hybridization technique capable of isolating rare mRNAs differentially expressed in two cell populations. cDNA-RDA can detect sequences represented at 0.0001% in the starting mRNA. By using reverse transcriptase polymerase chain reaction (PCR), cDNA-RDA also lends itself to studies in which samples are derived from limited numbers of cells. Standard cDNA-RDA protocols depend upon the presence of specific restriction enzyme sites in each cDNA, typically enzymes with four base recognition sequences. These sites are used to reduce the cDNA size range and provide primer sites for subsequent PCR amplification. Consequently, transcripts containing fewer than two of the chosen restriction sites are undetectable by cDNA-RDA. We have developed a restriction enzyme site-independent cDNA-RDA protocol called modified RDA (MRDA). We constructed MRDA test sequences from random hexamer-primed cDNA, thereby increasing the representation of mRNAs which are excluded by cDNA-RDA protocols. MRDA is also more efficient than cDNA-RDA at removing highly expressed housekeeping genes during the subtractive hybridization process, thereby allowing more efficient isolation of preferentially expressed mRNAs. Using MRDA, we isolated cDNAs differentially expressed between limited numbers of human CD4(+) naive and memory T lymphocyte subsets and skin- and gut-homing memory T cell subsets.

Cells↗