KLK3 and prostate cancer: Prostate-specific membrane antigen is a transmembrane glycoprotein highly overexpressed in prostate carcinoma, first described in 1983 by Horoszewicz et al. using LNCaP prostate carcinoma cells for immunization in a search for the identification of a prostate-specific antigen that could be used for immunohistochemical identification of prostate cancer cells [5].