C 22 represents an excellent marker for distinguishing carcinomas from all non-epithelial tumors. The antibody specifically reacts with keratins K5 and K8 present in nearly all epithelia. Polypeptide reacting: Mr 52 500, Mr 58 000 keratins (type II keratins K5 and K8; formerly also designated cytokeratins 5 and 8) of human epithelial cells. Epitope has been mapped to aa 353-367 on alpha helical rod domain of Keratin K8 (Waseem et al., 2004). Reactivity on cultured cell lines: MCF-7, RT 112, HT-29, Detroit 562, RPMI 2650, SSC-12, bovine BMGE+H, BMGE-H, MDBK Waseem A, Karsten U, Leigh IM, Purkis P, Waseem NH, Lane BE: Conformational changes in the rod domain of human keratin 8 following heterotypic association with keratin 18 and its implication for filament stability. Biochemistry 43, 1283-1295 (2004).