P504S, also known as α-Methylacyl coenzyme A racemase (AMACR), is a peroxisomal and mitochondrial enzyme that plays a role in bile acid synthesis and β-oxidation of branched chain fatty acids (1). AMACR was initially identified from a cDNA library as a gene that is over-expressed in human prostate cancer; with little or no expression in normal or benign prostate glands (2-3). In immunohistochemistry, P504S has been shown to be a marker of prostatic adenocarcinoma (2- 5). Additionally, prostate glands involved in prostatic intraepithelial neoplasia (PIN), have been found to express P504S; whereas P504S was nearly undetectable in benign glands. (5-6).