Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein which functions as a zinc metalloenzyme and is found on prostatic epithelium. In normal prostate tissue, PSMA expression and localization focuses on the cytoplasm and apical side of the epithelium surrounding prostatic ducts. However, during prostate carcinogenesis, PSMA is transferred to the luminal surface of the ducts.