Serine protease inhibitor. Inhibits TMPRSS7 (PubMed:15853774). Is a primary inhibitor of tissue-type plasminogen activator (PLAT) and urokinase-type plasminogen activator (PLAU). As PLAT inhibitor, it is required for fibrinolysis down-regulation and is responsible for the controlled degradation of blood clots (PubMed:8481516, PubMed:9207454, PubMed:17912461). As PLAU inhibitor, it is involved in the regulation of cell adhesion and spreading (PubMed:9175705). Acts as a regulator of cell migration, independently of its role as protease inhibitor (PubMed:15001579, PubMed:9168821). It is required for stimulation of keratinocyte migration during cutaneous injury repair (PubMed:18386027). It is involved in cellular and replicative senescence (PubMed:16862142). Plays a role in alveolar type 2 cells senescence in the lung (By similarity). Is involved in the regulation of cementogenic differentiation of periodontal ligament stem cells, and regulates odontoblast differentiation and dentin formation during odontogenesis (PubMed:25808697, PubMed:27046084). Forms a heterodimer with TMPRSS7 (PubMed:15853774). Interacts with VTN (PubMed:7522053). Binds LRP1B; binding is followed by internalization and degradation (PubMed:11384978). Interacts with PPP1CB (PubMed:28296156). In complex with PLAU/uPA, interacts with PLAUR/uPAR (PubMed:15053742). Interacts with SORL1 and LRP1, either alone or in complex with PLAU; these interactions are abolished in the presence of LRPAP1/RAP (PubMed:15053742). The ternary complex composed of PLAUR-PLAU-PAI1 also interacts with SORL1 (PubMed:15053742). Also interacts with SORL1, when complexed to PLAT/tPA (PubMed:15053742). Expressed in endothelial cells (PubMed:2430793, PubMed:3097076). Found in plasma, platelets, and hepatoma and fibrosarcoma cells. Inactivated by proteolytic attack of the urokinase-type (u-PA) and the tissue-type (TPA), cleaving the 369-Arg-|-Met-370 bond. The disease is caused by variants affecting the gene represented in this entry. A rare PAI-1D mutation resulting in a frameshift and protein truncation has been found in an Old Order Amish community. Homozygous mutation carriers suffer from episodes of major hemorrhage, while heterozygous carriers do not manifest abnormal bleeding (PubMed:9207454). Heterozygosity for the mutation is associated with longer leukocyte telomere length, lower fasting insulin levels, lower prevalence of diabetes mellitus, and a longer life span (PubMed:29152572). Belongs to the serpin family. Plasminogen activator inhibitor-1 entry Giving in to time - Issue 203 of May 2018