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M Seiki

Publications and source records attributed to M Seiki.

At least 73 records · Page 4Linked to original sources

MT1-MMP and MMP-2 mRNA expression in human ovarian tumors: possible implications for the role of desmoplastic fibroblasts.

Expression of activated MMP-2 (72 kDa type IV collagenase) is highly associated with the malignant phenotype in adenocarcinomas, but predominant expression of the mRNA appears to be in stromal cells. MT1-MMP (membrane type 1-matrix metalloproteinase) is implicated in tumor-epithelial cell surface activation of latent pro-MMP-2, indicating a mechanism for tumor-stromal interaction in invasion. We determined the relative mRNA distribution of these MMPs in human ovarian tumors with a view to analyzing potential variations in the epithelial-mesenchymal interactions dictating ovarian tumor cell spread. In situ hybridization using 35S-labeled riboprobes was used to analyze 33 human ovarian tumors and mouse xenografts of human ovarian (DOV 13, SKOV3) and breast (MCF 7) tumor cell lines known to express MT1-MMP and MMP-2. MMP-2 mRNA was expressed in 31 of 33 and MT1-MMP mRNA was expressed in 29 of 33 tumor cases. MMP-2 mRNA was predominantly expressed in desmoplastic fibroblasts and in the subepithelial stroma. MT1-MMP mRNA showed some colocalization with MMP-2 in stromal cells. Neoplastic epithelial cell labeling for MT1-MMP mRNA was present in borderline and malignant tumors but not in benign tumors, and was invariably less than stromal labeling. Xenografts of DOV 13, SKOV 3, and MCF 7 cells showed some stromal localization of MMP-2 mRNA and weak labeling of DOV 13 cells. There was variable labeling for MT1-MMP mRNA in the neoplastic cells only. The colocalization of MT1-MMP and MMP-2 mRNAs in ovarian carcinoma stroma supports the view that MT1-MMP is closely associated with MMP-2 expression and function. It suggests that either additional mechanisms are involved in regulating MMP-2 activation at the tumor cell surface, or more intriguingly, that desmoplastic fibroblasts may be the primary mediators of extracellular matrix remodeling with respect to this system.

Actins↗

Expression and localization of membrane type matrix metalloproteinase-1 (MT1-MMP) in trophoblast cells of cultured mouse blastocysts and ectoplacental cones.

Membrane type matrix metalloproteinases (MT-MMPs) possess a C-terminal transmembrane domain and are expressed on the cell membrane. It was suspected, therefore, that MT1-MMP might play an important role in the trophoblastic invasion during implantation. The patterns of expression and localization of membrane type matrix metalloproteinase-1 (MT1-MMP) were examined immunocytochemically in cultured mouse blastocysts and excised extoplacental cones (EPCs). MT1-MMP immuno-reactivity was present in the giant trophoblast cells located at the periphery of the spreading trophoblast of cultured blastocysts and the outgrowths of cultured EPCs, but not in the densely packed trophoblast cells in both the blastocysts and the EPCs. It appears likely that MT1-MMP expressed on the edge of the invading trophoblast facilitates the trophoblastic invasion by cleaving proMMP-2, a known substrate of MT1-MMP, in the decidua. Immunohistochemical examination of early conceptuses confirmed that the trophoblast cells actively invading the endometrium in vivo express MT1-MMP strongly. It is suggested, furthermore, that the expression of MT1-MMP might be downregulated by cell-cell contact in mouse trophoblast cells, as in the mouse mammary epithelial cell line HC11.

Animals↗

New collagenolytic enzymes/cascade identified at the pannus-hard tissue junction in rheumatoid arthritis: destruction from above.

Our aim was to investigate the collagenolytic potential and localization of matrix metalloproteinase-2 (MMP-2) in relation to its regulatory proteins membrane type MT1-MMP and tissue inhibitor of metalloproteinases-2 (TIMP-2) in rheumatoid arthritis (RA). For this purpose, we have used purification of MMP-2, MMP-8, MMP-9 and interstitial type I, II and III collagens; SDS-PAGE/densitometric collagenase activity assay; zymography; Western blotting; reverse transcriptase polymerase chain reaction; in situ hybridization; and immunofluorescence, ABC, ABC-APAAP double immunostainings. MMP-2 degraded human type II collagen almost as effectively as MMP-8, whereas MMP-9 did not cleave type II collagen. In synovial tissue, MT1-MMP, TIMP-2 and MMP-2 were found in synovial lining in fibroblast- and macrophage-like cells, in stromal cells and in vascular endothelium. MT1-MMP, TIMP-2 and MMP-2 were strongly expressed in the pannocytes of the invasive pannus at the interface, but staining was weak and/or there were few positive cells both "above" and "below" the soft-to-hard tissue (cartilage and/or bone) interface. Rheumatoid synovial tissue extract contained proteolytically active 62/59 kDa MMP-2 and 43 kDa MT1-MMP, but no free TIMP-2. These results indicate that components of the ternary MT1-MMP/TIMP-2/MMP-2 complex are coexpressed in the normal synovial lining and in its pathological extension on the hyaline articular cartilage. MMP-2 may participate in the remodeling of the normal lining and also seems to be localized/focalized to pannocytes at a site critical for tissue destruction in arthritis.

Adult↗

Tumor cell contact mediated transcriptional activation of the fibroblast matrix metalloproteinase-9 gene: involvement of multiple transcription factors including Ets and an alternating purine-pyrimidine repeat.

The 92-kDa type IV collagenase (MMP-9) is a metalloproteinase frequently localized in both tumor stroma and in tumor cells, particularly at the tumor invasion front. To explore the factors regulating transcriptional activation of MMP-9 in stromal cells, we used a model system in which fibroblast MMP-9 expression can be upregulated by cell-cell contact with metastatic transformed rat embryo cells. Using transient transfection of reporter gene constructs containing 5'-deleted or mutated MMP-9 promoter fragments, as well as electrophoretic mobility shift assays, the upstream NFkappaB, SP-1, and Ets sites and the downstream AP-1 site and retinoblastoma binding element were shown to be necessary for basal transcriptional activity of fibroblast MMP-9. In contrast only Ets or SP-1 appeared to be involved in contact-mediated induction of MMP-9. Mutation of the upstream AP-1 site increased both basal and contact-stimulated promoter activation. Deletion of the alternating purine-pyrimidine repeat in the downstream promoter decreased transcriptional activity. Together these findings suggest that Ets and SP-1 are the central transcriptional activators of MMP-9 gene expression in fibroblasts specifically responding to tumor cell contact, and that promoter conformation may regulate MMP-9 expression.

Animals↗

Elevated cyclic AMP suppresses ConA-induced MT1-MMP expression in MDA-MB-231 human breast cancer cells.

We have previously reported that induction of MMP-2 activation by Concanavalin A (ConA) in MDA-MB-231 human breast cancer cells involves both transcriptional and post-transcriptional mechanisms, and that the continuous presence of ConA is required for MMP-2 activation (Yu et al. Cancer Res, 55, 3272-7, 1995). In an effort to identify signal transduction pathways which may either contribute to or modulate this mechanism, we found that three different cAMP-inducing agents, cholera toxin (CT), forskolin (FSK), and 3-isobutyl-1-methylxanthine (IBMX) partially inhibited ConA-induced MT1-MMP expression and MMP-2 activation in MDA-MB-231 cells. Combinations of CT or FSK with IBMX exhibited additive effects on reduction of MT1-MMP mRNA expression and MMP-2 activation. Agents which increase cAMP levels appeared to target transcriptional aspects of ConA induction, reducing MT1-MMP mRNA and protein in parallel with the reduced MMP-2 activation. In the absence of ConA, down-regulation of constitutive production of MT1-MMP mRNA and protein was observed, indicating that cAMP acts independently of ConA. These observations may help to elucidate factors regulating MT1-MMP expression, which may be pivotal to the elaboration of invasive machinery on the cell surface.

Breast Neoplasms↗

Role of tissue inhibitor of metalloproteinases-2 (TIMP-2) in regulation of pro-gelatinase A activation catalyzed by membrane-type matrix metalloproteinase-1 (MT1-MMP) in human cancer cells.

To clarify the regulatory mechanism of pro-gelatinase A (proGelA) activation at a cellular level, expression of gelatinase A (GelA), three MT-MMPs, and TIMP-2 was examined with 11 human cancer cell lines cultured in the presence and absence of stimulants. MT1-MMP mRNA was expressed in 8 cell lines, while MT2-MMP and MT3-MMP mRNAs were expressed in fewer cell lines. The cells with high proGelA activation strongly expressed MT1-MMP mRNA but not MT2-MMP and MT3-MMP mRNAs, suggesting that MT1-MMP was responsible for the proGelA activation in the cancer cells. Treatments with concanavalin A (Con A) and a phorbor ester (TPA) enhanced the MT1-MMP expression, but only Con A stimulated the proGelA activation in many cell lines. In HT1080 fibrosarcoma cells, however, TPA also stimulated the activation. The level of TIMP-2 secreted into culture medium inversely correlated with proGelA activation. For example, 2 squamous cell carcinoma lines (HSC-3 and HSC-4) and 3 HT1080 clones, which efficiently activated proGelA, secreted little TIMP-2 into medium, whereas other cell lines and other HT1080 clones, which hardly activated proGelA, secreted TIMP-2 at high levels. When HSC-3 cells were incubated with TIMP-2 protein or transfected with TIMP-2 cDNA, the proGelA activation was strongly inhibited. These results indicated that extracellular TIMP-2 was an important negative regulator of proGelA activation. However, the level of extracellular TIMP-2 was not consistent with that of TIMP-2 mRNA in some cell lines. Other experimental results suggested that TIMP-2 might be rapidly metabolized after binding to MT1-MMP, and Con A treatment might stabilize the complex of TIMP-2 and MT1-MMP on cell membranes.

Catalysis↗

Production of membrane-type matrix metalloproteinase-1 (MT-MMP-1) in early human placenta. A possible role in placental implantation?

The extracellular matrix proteolytic machinery is known to play a major role in trophoblast invasion, a process that shares similar features with the pathology of tumor invasion. In this study we investigated the expression of the recently described membrane-type matrix metalloproteinase-1 (MT-MMP-1; MMP-14) in early human placenta and decidual membrane to determine whether it might play a role in invasion. With in situ hybridization, the cytotrophoblasts of trophoblastic columns and the infiltrating intermediate trophoblasts in the decidual membrane were found to be the main producers of MT-MMP-1 mRNA. Gene expression was also seen in the villous double-layered trophoblastic epithelium and in the decidual cells of the decidual membrane. In endothelial and fibroblastic cells, however, the hybridization signal was either very weak or nonexistent. Immunohistochemical analysis and immunoelectron microscopy correlated well with the in situ hybridization findings. The most significant exception to this consisted of pericytes of spiral arteries, which appeared to lack MT-MMP-1 mRNA but showed intensive intracytoplasmic staining for the antigen. Our results show that MT-MMP-1 mRNA production is highly characteristic of intermediate trophoblasts, and MT-MMP-1 may have general importance in the tissue organization of early human placenta. We propose that MT-MMP-1 could be one of the key enzymes in the process of trophoblast invasion, acting alone or as a cell-surface activator of other proteinases.

Chorionic Villi↗

Expression and tissue localization of membrane-types 1, 2, and 3 matrix metalloproteinases in human urothelial carcinomas.

PURPOSE: Three different membrane-type matrix metalloproteinases (MT1, 2, 3-MMP) which can activate proMMP-2 (progelatinase A) are thought to have an important role in various human carcinoma invasions and metastases. We examined the mRNA expression of MT-MMPs and the tissue immunolocalization of MT1-MMP in human urothelial carcinomas. MATERIALS AND METHODS: mRNA was extracted from 27 clinical urothelial carcinomas and 10 normal urothelial mucosa tissues remote from the tumor. RT-PCR using specific primers was performed, and PCR products were hybridized to 32P-labeled internal probes and analyzed by a bioimage analyzer. Immunolocalization was studied using a monoclonal antibody against MT1-MMP (114-6G6). RESULTS: MT1-MMP and MT2-MMP mRNA expressions in urothelial carcinomas were significantly higher than those in the normal mucosa. In contrast, MT3-MMP mRNA was little expressed in both tissues, and the amount of MT3-MMP mRNA appeared to be much lower than MT1-MMP and MT2-MMP in the tissue samples. In terms of the tumor multiplicity, MT1-MMP and MT2-MMP mRNA expressions in the group of multiple tumors were significantly higher than those in the solitary tumor group. The carcinoma cells were immunostained for MT1-MMP predominantly in invasive and superficial carcinoma cells. The immunoreactivity was more intense in the invasive type than in the superficial type. CONCLUSIONS: It is suggested that MT1-MMP and MT2-MMP play an important role in the development of human urothelial carcinomas and reflect some aspects of the pathogenesis of multifocal occurrence. In spite of the possible contribution to the invasive and metastatic phenotype, MT1-MMP mRNA and its product are thought to be expressed already in the clinical superficial stage in some cases of this tumor type.

Carcinoma, Transitional Cell↗

Tyrosine phosphorylation mediates ConA-induced membrane type 1-matrix metalloproteinase expression and matrix metalloproteinase-2 activation in MDA-MB-231 human breast carcinoma cells.

ConA-induced cell surface activation of pro-matrix metalloproteinase-2 (pro-MMP-2) by MDA-MB-231 human breast cancer cells is apparently mediated by up-regulation of membrane type 1 MMP (MT1-MMP) through transcriptional and posttranscriptional mechanisms. Here, we have explored the respective roles of cell surface clustering and protein tyrosine phosphorylation in the ConA-induction effects. Treatment with succinyl-ConA, a variant lacking significant clusterability, partially stimulated MT1-MMP mRNA and protein levels but did not induce MMP-2 activation, suggesting that clustering contributes to the transcriptional regulation by ConA but appears to be critical for the nontranscriptional component. We further found that genistein, an inhibitor of tyrosine phosphorylation, blocked ConA-induced pro-MMP-2 activation and ConA-induced MT1-MMP mRNA level in a dose-dependent manner, implicating tyrosine phosphorylation in the transcriptional aspect. This was confirmed by the dose-dependent promotion of pro-MMP-2 activation by sodium orthovanadate in the presence of suboptimal concentrations of ConA (7.5 microg/ml), with optimal effects seen at 25 microg/ml orthovanadate. Genistein did not inhibit the ConA potentiation of MMP-2 activation in MCF-7 cells, in which transfected MT1-MMP is driven by a heterologous promoter, supporting the major implication of phosphotyrosine in the transcriptional component of ConA regulation. These data describe a major signaling event upstream of MT1-MMP induction by ConA and set the stage for further analysis of the nontranscriptional component.

Concanavalin A↗

Regulation of collagenase-3 expression in human breast carcinomas is mediated by stromal-epithelial cell interactions.

Collagenase-3 (MMP-13) is a recently identified member of the human matrix metalloproteinase gene family that is expressed in breast carcinomas and in articular cartilage from arthritic patients. Here, we have studied the cellular origin of this enzyme in breast carcinomas by in situ RNA hybridization, and we found that collagenase-3 is expressed by stromal cells immediately adjacent to epithelial tumor cells but not by the tumor cells themselves; nor is it expressed by the normal breast glandular epithelium. Consistent with this observation, coculture experiments using human fibroblasts and MCF-7 breast cancer cells revealed that conditioned medium from breast cancer cells stimulated the fibroblastic expression of collagenase-3 mRNA. In contrast, no stimulatory effect was observed when medium from fibroblast cells was added to breast cancer cells. These results strongly suggest that transcription of collagenase-3 in stromal cells is activated by diffusible factors released from epithelial breast cancer cells. A survey of a series of cytokines and growth factors known for their ability to induce collagenase-3 expression in human fibroblasts identified interleukin-1alpha and interleukin-1beta as potential candidates for inducing the expression of this MMP gene in breast carcinomas. According to these results, collagenase-3 should be included among the molecular factors that are detected during the stromal reaction to invasive breast cancer and that, by concerted action, may be essential for tumor growth and progression.

Breast Neoplasms↗

Calcium influx inhibits MT1-MMP processing and blocks MMP-2 activation.

We have previously reported that concanavalin A (ConA)-induced MMP-2 activation involves both transcriptional and non-transcriptional mechanisms. Here we examined the effects of calcium influx on MT1-MMP expression and MMP-2 activation in MDA-MB-231 cells. The calcium ionophore ionomycin caused a dose-dependent inhibition of ConA-induced MMP-2 activation, but had no effect on MT1-MMP mRNA levels. However, Western analysis revealed an accumulation of pro-MT1-MMP (63 kDa), indicating that ionomycin blocked the conversion of pro-MT1-MMP protein to the active 60 kDa form. This suggests that increased calcium levels inhibit the processing of MT1-MMP. This finding may help to elucidate the mechanism(s) which regulates MT1-MMP activation.

Blotting, Northern↗

Transmembrane/cytoplasmic domain-mediated membrane type 1-matrix metalloprotease docking to invadopodia is required for cell invasion.

The invasion of human malignant melanoma cells into the extracellular matrix (ECM) involves the accumulation of proteases at sites of ECM degradation where activation of matrix metalloproteases (MMP) occurs. Here, we show that when membrane type 1 MMP (MT-MMP) was overexpressed in RPMI7951 human melanoma cells, the cells made contact with the ECM, activated soluble and ECM-bound MMP-2, and degraded and invaded the ECM. Further experiments demonstrated the importance of localization of the MT-MMP to invadopodia. Overexpression of MT-MMP without invadopodial localization caused activation of soluble MMP-2, but did not facilitate ECM degradation or cell invasiveness. Up-regulation of endogenous MT-MMP with concanavalin A caused activation of MMP-2. However, concanavalin A treatment prevented invadopodial localization of MT-MMP and ECM degradation. Neither a truncated MT-MMP mutant lacking transmembrane (TM) and cytoplasmic domains (DeltaTMMT-MMP), nor a chimeric MT-MMP containing the interleukin 2 receptor alpha chain (IL-2R) TM and cytoplasmic domains (DeltaTMMT-MMP/TMIL-2R) were localized to invadopodia or exhibited ECM degradation. Furthermore, a chimera of the TM/cytoplasmic domain of MT-MMP (TMMT-MMP) with tissue inhibitor of MMP 1 (TIMP-1/TMMT-MMP) directed the TIMP-1 molecule to invadopodia. Thus, the MT-MMP TM/cytoplasmic domain mediates the spatial organization of MT-MMP into invadopodia and subsequent degradation of the ECM.

Amino Acid Sequence↗

Expression and tissue localization of membrane-types 1, 2, and 3 matrix metalloproteinases in human invasive breast carcinomas.

Activation of the zymogen of matrix metalloproteinase 2 (proMMP-2, progelatinase A) possibly is one of the key steps in invasion and metastasis of various human carcinomas. Three different membrane-type MMPs (MT-MMPs), MT1-, MT2-, and MT3-MMPs are thought to be activators of proMMP-2 in the tissues. MT4-MMP is structurally different from the other three enzymes, and its function as proMMP-2 activator is uncertain. In the present study of human invasive breast carcinomas, we examined a correlation between the expression of MT1-, MT2-, and MT3-MMPs, immunolocalization of MT1- and MT2-MMPs, and proMMP-2 activation. Northern blot analysis demonstrated the predominant expression of MT1-MMP mRNA in carcinoma tissues (20 of 20 cases), whereas MT2-MMP was detected in only 25% of the cases (5 of 20 cases), and no detectable expression of MT3-MMP was observed. The expression levels of MT1-MMP but not MT2-MMP correlated well with the presence of lymph node and distant metastases, clinical stages, and size of tumors. Immunohistochemically, MT1-MMP was localized predominantly in the carcinoma cells in all of the samples (32 of 32 cases). Immunostaining of MT2-MMP in the carcinoma cells was observed in only 38% of the cases (12 of 32 cases). Immunoblot analysis of tumor homogenates confirmed the presence of these MT-MMPs. Activation of proMMP-2 was significantly higher in the carcinoma samples with lymph node or distant metastasis compared to carcinoma without metastasis, normal control, or fibrocystic disease (P < 0.05). An increase in the activation ratio of proMMP-2 correlated directly with the expression of MT1-MMP but not MT2-MMP, as measured by either Northern blot analysis or immunostaining. These results suggest that MT1-MMP may play a key role in human breast carcinoma invasion and metastasis by being predominantly responsible for activation of proMMP-2.

Adult↗

Transcriptional activation of the matrix metalloproteinase-9 gene in an H-ras and v-myc transformed rat embryo cell line.

The 92 kd type IV collagenase/gelatinase (MMP-9) is important in mediating basement membrane and extracellular matrix degradation in metastasis. Because MMP-9 is made in tumor cells, but not in quiescent normal cells, we wished to identify the transcriptional elements responsible for its synthesis in tumor cells. We chose to characterize transcriptional regulation of the MMP-9 gene in a highly metastatic H-ras and v-myc transformed rat embryo cell line which overexpresses MMP-9. Using transient transfection of reporter gene constructs containing either 5'-deleted or mutated MMP-9 promoter fragments, as well as electrophoretic mobility shift assays, we have demonstrated that multiple transcription factor consensus binding motifs in the promoter, including those for NFkappaB, SP-1, Ets, AP-1, and a retinoblastoma binding element, participate in transcriptional regulation of MMP-9 expression in this cell line. Also, deletion of an alternating purine-pyrimidine tract in the downstream promoter was found to decrease transcriptional activity, suggesting that promoter conformation may be important in MMP-9 regulation. Thus multiple pathways leading to activation of NFkappaB, SP-1, Ets, AP-1, and retinoblastoma binding factors in tumor cells all may contribute to MMP-9 transcription and hence to metastasis.

Animals↗

A BALB/c 3T3-transformed cell line suitable for transfection assay of metastasis-inducing genes.

A clonal cell line, 1-1ras1000, transformed by the activated c-Ha-ras oncogene, does not form metastases after i.v. injection into mice (experimental metastasis assay). Here, we show that this cell line is useful as a recipient to detect metastasis-inducing genes, using a transfection assay. Cells (1-1ras1000) were susceptible to metastasis induction by transfection with either v-src or genomic DNA from a v-src-and v-fos-transferred highly metastatic rat cell line (SR202). The susceptibility of 1-1ras1000 cells for lung metastasis induction was suitable for a genomic transfection assay to detect a metastasis-inducing gene in the transfected cells which had incorporated genomic DNA from donor metastatic tumor cells. When DNAs extracted from 7 human tumors were tested for metastasis induction, 2 DNAs from nonmalignant tumors (non-tumorigenic tumors in athymic nude mice) (2/2) were negative and 4 DNAs from malignant tumors (4/5) were positive in 1-1ras1000 cells for primary transfection. in one of the resulting metastases, the ability to metastasize was also transferred in the second and third cycles of genomic DNA transfection at high frequencies. All of the resulting metastases carried the human repetitive Alu sequence. Neither re-arrangements of the endogenous c-Haras nor changes of protein amounts were detected. Recipient 1-1ras1000 cells had a negligible rate of spontaneously metastatic conversion during in vitro cultivation and transfection processes. The resulting metastasized cells were easily isolated from the lung after culturing in selection medium containing G418 (geneticin). Isolated cells stably retained the ability to form metastatic lung nodules when re-injected into mice. Thus, 1-1ras1000 cells appear to be a useful system for the isolation of metastasis-inducing genes from human metastatic tumors.

3T3 Cells↗

Proteolytic activation of the precursor of membrane type 1 matrix metalloproteinase by human plasmin. A possible cell surface activator.

Membrane type 1 matrix metalloproteinase (MT1-MMP) was suggested to play a critical role in the regulation of tissue invasion by normal and neoplastic cells by directly mediating the activation of pro-gelatinase A. Recently, the proteolytic activation of a pro-MT1-MMP by an intracellular proprotein convertase, furin, was reported. In this study, we found that plasmin efficiently activates the pro-MT1-MMP by cleaving immediately downstream of Arg108 and Arg111 in the multi-basic motif between its pro- and catalytic domains that participates in the activation of pro-gelatinase A. Our present data suggest that pro-MT1-MMP transported to the plasma membrane is activated by plasmin extracellularly and thus it may play an important role in the matrix degradation process.

Amino Acid Sequence↗

Isolation of a mouse MT2-MMP gene from a lung cDNA library and identification of its product.

We have isolated a new MT-MMP related gene of 3.3 kb from a mouse lung cDNA library using a human MT1-MMP cDNA as a probe. The deduced protein sequence shows 87% homology to human MT2-MMP and 52, 50 and 29% to MT1-MMP, MT3-MMP and MT4-MMP, respectively. Thus the gene is thought to be a mouse homologue of human MT2-MMP. A monoclonal antibody raised against a synthetic peptide recognized mouse MT2-MMP as a 70 kDa protein. Like MT1- and MT3-MMPs, mouse MT2-MMP caused activation of progelatinase A upon co-transfection into COS-1 cells.

Amino Acid Sequence↗