MUC5AC and intrahepatic cholangiocarcinoma: Several additional genes alternations in ICC pathogenesis have been investigated including intermediate filaments (CK-7,-17,-19,-20), markers of pancreaticobiliary and gastrointestinal origin (CA19-9, mCEA, and CA125), mucins (MUC2 and MUC5AC) and tumor suppressor protein SMAD4 [56].