MUC4 and pancreatic intraductal papillary-mucinous neoplasm: Notably, several genes outperformed MUC1 and MUC4 as IPMN subtype marker genes, including clusterin (CLU), retinol binding protein 4 (RBP4), and keratin 17 (KRT17), which showed marked overexpression in GF, INT, and PB AOIs, respectively (Fig. 3C).