PAI1 (plasminogen activator inhibitor 1) is originally cloned from human endothelial cell (Pannekoek 1986, Ginsburg 1986) and rat hepatoma cell 3 cDNA libraries. As a member of the serpin family of serine protease inhibitors, PAI1 inhibits both tissue type plasminogen activator (tPA) and urokinase type plasminogen activator (uPA). High PAI1 levels are associated with an increased risk of thromboembolic disease while PAI1 deficiency may represent an inherited autosomal recessive bleeding disor