SMAD4 and pancreatic intraductal papillary-mucinous neoplasm: Because we have previously shown that increased SMAD4 expression at the protein level can be induced by the transfection of WWOX-expressing vector into pancreatic cancer-derived PANC-1 cells (Nakayama et al, 2008), we also examined the SMAD4 expression in these IPMN cases (Figure 3A).