MUC5AC and pancreatic intraductal papillary-mucinous neoplasm: The precursor lesions may be of the intraductal papillary mucinous neoplasia type (IPMN, mucin producing neoplastic cells located in the duct), mucinous cystic neoplasia type (MCN, mucin producing neoplastic cells that do not connect to the duct), and pancreatic intraepithelial neoplasia type (PanIN, cells with non-invasive microscopic epithelial neoplasm), with the latter being the most common precursor in humans (8, 24, 25, 27).