Importantly, we sequenced the entire coding regions for Ras (Hras, Kras, Nras) and found no mutations in any of the tumors in PLX4720-treated mice, as compared to one of 14 papillomas and carcinomas in a cohort of control-treated chronically-irradiated Hairless mice (Figure 5—figure supplement 1). This evidence concerns the gene KRAS and papilloma.