This gene encodes a member of the parvulin subfamily of the peptidyl-prolyl cis/trans isomerase protein family. The encoded protein catalyzes the isomerization of peptidylprolyl bonds, and may play a role in the cell cycle, chromatin remodeling, and/or ribosome biogenesis. The encoded protein may play an additional role in the mitochondria. This antibody recognizes Prostate Intraepithelial Neoplasia (PIN) in the tissues stained by immunohistochemical techniques. A cocktail of thesethree antibodies might allow simultaneous demonstration of P504S, HMWCK and p63 using a single immunostain. The combination of P504S +HMW CK + p63 (PIN4 Cocktail) may be extremely useful for studying prostatic intraepithelial neoplasia, especially in difficult cases and in cases with limited tissue.