Also, tumor glands showed positive staining for racemase (alpha-methylacyl-CoA racemase, also known as AMACR or P504S; encoded by the AMACR gene), negative (or weakly positive) staining for CK5 (a prostate basal epithelial marker), and negative staining for p63 (another basal cell marker) (Fig. 2A). Here, AMACR is linked to neoplasm.