SMAD4 and pancreatic intraductal papillary-mucinous neoplasm: TGF-β/SMAD4 signaling may therefore have pleiotropic and context-dependent roles in IPMN and the present study suggested that determining the TGF-β and/or SMAD4 status of a tumor at initial diagnosis may be of value for stratifying patients into treatment regimens (surgical management vs. conservative follow-up).