PAI-1 (plasminogen activator inhibitor-1) is originally cloned from human endothelial cell and rat hepatoma cell cDNA libraries. As a member of the serpin family of serine protease inhibitors, PAI-1 inhibits both tissue-type palsminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA). High PAI-1 levels are associated with an increased risk of thromboembolic disease while PAI-1 deficiency may represent an inherited autosomal recessive bleeding disorder.
