KRAS and pancreatic ductal adenocarcinoma: After in vivo transplantation, PDLOs with oncogenic KRAS form heterogeneous dysplastic lesions, PDLOs carrying oncogenic KRAS with CDKN2A knockout give rise to pancreatic ductal adenocarcinomas, and PDLOs carrying oncogenic GNAS form intraductal papillary mucinous neoplasia-like structures.