Intermediate-sized filament (IF) protein designated cytokeratin (CK) 20 is a major cellular protein of matureenterocytes and goblet cells commonly found in mucosal epithelium of the mammalian gastrointestinal tract.Results strongly suggest that transcriptional regulation of keratin genes in the intestinal epithelium occurs atthe level of both immature and terminally differentiated epithelial cells, and is tightly regulated during both fetaldevelopment and crypt-to-villus differentiation of the intestinal epithelium. CK20 has recently been reported tobe useful to distinguish between primary and metastatic lung adenocarcinoma. CK20 expression wassignificantly more prevalent in adenocarcinoma that originated in the GI tract than that of pulmonary or breastorigin.
