Indeed, the initial cloning of the cDNA encoding the gene expressing PSMA was accomplished with RNA from a prostate tumor cell line, LNCaP. PSMA shares homology with the transferrin receptor and undergoes endocytosis but the ligand for inducing internalization has not been identified. It was found that PSMA was the same as the membrane protein in the small intestine responsible for removal of gamma-linked glutamates from polygammaglutamate folate. This enables the freeing of folic acid, which then can be transported into the body for use as a vitamin. This resulted in the cloned genomic designation of PSMA as FOLH1 for folate hydrolase.