SMAD4 and pancreatic intraductal papillary-mucinous neoplasm: Recent development of GEM models revealed that adding Smad4 deletion to KRASG12D mutation (KrasG12D:Smad4L/L:Ptf1a-Cre), both of which target the pancreatic epithelium, leads to tumors that resemble human intraductal papillary mucinous neoplasms (IPMN) [4]; this GEM model is referred to as CKS.