MUC5AC and pancreatic intraductal papillary-mucinous neoplasm: Staining was predominantly apical and extracellular with mature (21 M1/Nd2 mab) and perinuclear/cytoplasmic with immature (CLH2 mab) MUC5AC across PanINs and cancers, proving that they exist in precancerous (PanIN and IPMN) and PDAC tissues.