Antibody therapy is now common for several diseases. Some unique antibodies contain a protease function, with the ability to specifically degrade their target antigen. IntegriGen has cloned unique proteolytic antibody genes and will engineer them to bind and cleave therapeutically relevant target antigens. This project has three specific aims: 1) Clone and engineer libraries of proteolytic antibodies, 2) synthesize fluorophosphonate probes capable of specifically binding active proteases, and 3) screen the libraries of aim (1) against the model tumor antigen VEGF and the fluorophosphonate probe of aim (2) to discover new antigen specific proteolytic antibodies. ? ? ?