KRAS and cancer: Whole-exome sequencing of lung tumors driven by endogenous Kras oncogenes has revealed a relatively modest number of co-occurring mutations, including a significant fraction of tumors lacking additional mutations in other known cancer genes (Chung et al, 2017; Junttila et al, 2010; McFadden et al, 2016; Westcott et al, 2015).