HNF4A and pancreatic intraductal papillary-mucinous neoplasm: Similarly, HNF4α nuclear expression in poorly differentiated invasive IPMN was lower than in high-grade non-invasive IPMN across all isoform groups: pan-promoter (p = 0.0002), P1 (p = 0.0087), and P2 (p < 0.0001).