SMAD4 and pancreatic intraductal papillary-mucinous neoplasm: PAAD is known to progress through precursor lesions, primarily pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN), whose genetic evolution involves recurrent driver mutations such as KRAS, TP53, CDKN2A, and SMAD4 [7,8,9].