SMAD4 and pancreatic intraductal papillary-mucinous neoplasm: IPMN are known to harbor mutations of KRAS [5, 6], p16 [6], p53 [5], GNAS [7], RNF43 [8], and DPC4/SMAD4/MADH4 [9], but the prevalence of the mutations is lower than in pancreatic ductal adenocarcinoma (PDAC).