MUC5AC and pancreatic ductal adenocarcinoma: MUC2 has been found to be expressed mainly in the noninvasive tumors such as intraductal papillary mucinous neoplasm of the pancreas (IPMN) and mucin-producing bile duct tumor (MPBT) [10,36], whereas MUC2 does not appear to be expressed in pancreatic ductal adenocarcinoma [37].