SERPINE1,also named as Plasminogen activator inhibitor type 1 (PAI-1),is a member of the serine protease inhibitor (SERPIN) superfamily. PAI-1 is the principal inhibitor of tissue plasminogen activator (tPA) and urokinase (uPA),and hence is an inhibitor of fibrinolysis. Defects in this gene are the cause of plasminogen activator inhibitor-1 deficiency (PAI-1 deficiency),and high concentrations of the gene product are associated with thrombophilia.