MUC5AC and pancreatic serous cystadenoma: MUC5AC is expressed or upregulated in many benign biliary disease tissues, as detected using immature CLH2 or M5P-b1 antibodies, mature 45M1 antibodies, or polyclonal Dako antibodies, including primary sclerosing cholangitis (PSC), hepatolithiasis, recurrent pyogenic cholangitis, bile duct adenomas, gallbladder adenomas, and chronic cholecystitis [80,84,90,94,96,97,98,99,100].