PAI‐1, progress in understanding the clinical problem and its aetiology

Summary Plasminogen activator inhibitor‐1 ( PAI ‐1, also known as SERPINE 1) is a member of the serine protease inhibitor ( SERPIN ) superfamily and is the primary physiological regulator of urokinase‐type plasminogen activator (u PA ) and tissue‐type plasminogen activator (t PA ) activity. Although the principal function of PAI ‐1 is the inhibition of fibrinolysis, PAI ‐1 possesses pleiotropic functions besides haemostasis. In the quarter century since its discovery, a number of studies have focused on improving our understanding of PAI ‐1 functions in vivo and in vitro . The use of Serpine1 ‐ deficient mice has particularly enhanced our understanding of the functions of PAI ‐1 in various physiological and pathophysiological conditions. In this review, the results of recent studies on PAI ‐1 and its role in clinical conditions are discussed.