APC and adenocarcinoma: Intriguingly, while Paneth cells are not present in normal colon epithelium, Paneth cell “metaplasia” has been reported in proximal colon epithelium in adenomas, adenocarcinoma, and inflammatory bowel disease, and ectopic Paneth cells were observed in colon epithelium of Apc-deficient mouse models (73, 74, 85, 86).