FOLH1 and prostate cancer: Prostate specific membrane antigen (PSMA) is a 100 kDa type II transmembrane glycosylated protein with folate hydrolase activity and is overexpressed not only in nearly all prostate cancer cells,6 but also in tumor neovasculature in a variety of cancers.6–8 In contrast, it has minimal expression (100–1000 times lower) in normal prostate epithelium tissues and other normal tissues,7,9 making it an ideal biomarker for the design of various targeted therapies.