Urokinase-type plasminogen activator is a serine protease with extremely limited substrate specificity, cleaving the sequence Cys-Pro-Gly-Arg560-Val561-Val-Gly-Gly-Cys in plasminogen to form plasmin. It is a potent marker of invasion and metastasis in a variety of human cancers associated with breast, stomach, colon, bladder, ovary, brain and endometrium.
