PMEPA1 and colorectal neoplasm: Consistent with the expression profile of ERBB3, the expression levels of PMEPA1, which is a marker of terminally differentiated cells exclusively found at the surface of colonic epithelial crypts, are increased in colorectal tumours compared to normal tissues [32], suggesting that molecules that mark differentiated cell population can also be elevated in some cases during colorectal carcinogenesis.