KRAS and neoplasm: Of note, Makoto and his colleagues showed that activated WNT signaling in the tumor stromal microenvironment contributes to the development of murine pancreatic MCNs in Ptf1a-Cre-LSL-Kras-elastase-tva mice injected with replication-competent-avian-sarcoma (RCAS)-WNT1 viruses [37].