GNAS and pancreatic intraductal papillary-mucinous neoplasm: GNAS mutations were detected in 50% of PDAC cases that were concomitant with IPMN (p = 0.0007 vs. PDAC without IPMN), 33.3% of PDAC cases that were derived from IPMN (p = 0.03 vs. PDAC without IPMN), and 66.7% of IPMN cases (p = 0.0004 vs. PDAC without IPMN), while no GNAS mutations were detected in cases of PDAC without IPMN.