FOLH1 and prostate cancer: A weak extra prostatic expression of PSMA has been reported in some other tissues (Renneberg et al. 1999; Silver et al. 1997) Therefore, the Hu591 monoclonal antibody(mAb) targeting the PSMA extracellular domain, has been applied to the prostate cancer therapy (Liu et al. 1997; Nanus et al. 2003).