MUC5AC and pancreatic intraductal papillary-mucinous neoplasm: While there appears to be no conclusive evidence that tissue-based MUC5AC IHC detection is reliable, Yonezawa et al. studied MUC5AC gene expression (mRNA using in situ hybridization) in intrapapillary mucinous neoplasms (IPMN) and PDAs [61].