Prostate cancer has a high predilection for metastasizing to bone, and often produces a ”blastic” bone response. We hypothesize that the expression or production of prostate proteases in ectopic sites (such as bone), contribute to this disease process. The prostate produces several proteases in a highly tissue-specific fashion including several novel proteases identified in our laboratory. Current studies are designed to characterize the substrate specificities of these proteases in order to determine if they may play a role in modulating carcinogenesis (invasion/metastasis) and serve as drug targets. We are also characterizing the function of several proteases through the use of transgenic mice.