FOLH1 and prostate cancer: PSMA, also known as glutamate carboxypeptidase II, is a type II transmembrane glycoprotein which consists of 750 amino acids and is encoded by the FOLH1 (folate hydrolase 1) gene.15 In prostatic tissue, PSMA is expressed in the secretory epithelial cells, and PSMA is overexpressed in prostate cancer.