Description: p504S (AMACR, alphamethylacyl-CoA-Racemase) is an enzyme involved in beta-oxidation of branchedchain fatty acids. It is expressed in prostatic adenocarcinomas but not in benign glands. Detection of p504S is helpful in distinguishing malignant from benign cells. P63 is detectable in benign basal cells of the prostate and in other epithelial tissues. Combined detection of p504S and p63 is useful for the diagnosis of prostate cancers. Anti-p504S is positive in cytoplasm of malignant and pre-malignant prostate glands, anti-p63 antibody is positive in benign glandular basal layer nuclei.