AMACR (P504S) is an acronym for the protein alpha-methylacyl CoA racemase that helps to metabolize certain fatty acids within the body. AMACR has been recently described as a prostate cancer-specific gene that encodes a protein involved in the beta-oxidation of branched chain fatty acids. Expression of AMACR protein is found in Prostatic Adenocarcinoma but not in benign prostatic tissue. It stains premalignant lesions of the prostate: High-Grade Prostatic Intraepithelial Neoplasia (PIN) and Atypical Adenomatous Hyperplasia. Several studies have suggested that AMACR can be used as a prostate cancer biomarker.

High expression of AMACR (P504S) protein is usually found in Prostatic Adenocarcinoma but not in benign prostatic tissue by immunohistochemical staining in paraffin-embedded tissues. Using AMACR as a positive marker along with basal-cell staining (34βE12 or p63) as a negative marker could help to confirm the diagnosis of small foci of Prostate Carcinoma on needle biopsies. ^1-5