Various immunohistochemical stains, including prostate-specific antigen (PSA), prostate specific acid phosphatase/prostatic acid phosphatase (PSAP/PAP), NKX3.1, P501S, prostate-specific membrane antigen (PSMA), androgen receptor (AR), and alpha methyacyl CoA racemase (AMACR), are available, which can help to differentiate prostatic adenocarcinoma from carcinomas from other organs. The gene discussed is FOLH1; the disease is carcinoma.