EMMPRIN (CD147) is a cell surface protein that is highly expressed on tumor cells. Elevated EMMPRIN levels have been detected in a variety of malignant tumors and have been associated with tumor progression in experimental and clinical conditions. Recent studies have shown that EMMPRIN is an independent prognostic factor for overall survival in bladder cancer patients. In a multicenter phase II trial, antibodies against EMMPRIN were shown to be successful in hepatocellular cancer therapy. We are characterizing the functional importance of EMMPRIN in bladder cancer in order to evaluate this protein as a new target molecule for therapy.