HNF4A and pancreatic intraductal papillary-mucinous neoplasm: However, HNF4α nuclear expression was markedly lower in poorly differentiated invasive IPMN compared to well-differentiated invasive IPMN across all isoform groups: pan-promoter (p < 0.0001), P1 (p = 0.0066), and P2 (p = 0.0001) (Fig. 2a,b).