Disclosed is a method of identifying a candidate inhibitor substance that inhibits hepsin activation of pro-urokinase type plasminogen activator (pro-uPA), said method comprising: (a) Contacting a candidate substance with a first sample comprising hepsin and a pro-uPA substrate, and (b) Comparing amount of pro-uPA substrate activation in the sample with amount of pro-uPA substrate activation in a reference sample comprising similar amounts of hepsin and pro-uPA substrate as the first sample but that has not been contacted with said candidate substance, whereby a decrease in amount of pro-uPA substrate activation in the first sample compared to the reference sample indicates that the candidate substance is capable of inhibiting hepsin activation of single chain uPA (pro-uPA).
