Fibrin deposition and fibrinolysis must be balanced during repair of an injured blood vessel wall. Injured vascular endothelial cells release plasminogen activators (tissue plasminogen activator, urokinase), activating fibrinolysis. Plasminogen activators cleave plasminogen into plasmin, which dissolves clots. Fibrinolysis is controlled by plasminogen activator inhibitors (PAIs; eg, PAI-1) and plasmin inhibitors (eg, alpha 2-antiplasmin).