C-OSKM mice treated with Dox for 1–2 weeks also developed undifferentiated cancer in the stomach (Supplementary Fig. 8B, C), albeit at lower frequency than KC-OSKM mice (p < 0.01, Fisher’s exact test, Supplementary Table 1), suggesting that the Kras mutation promotes but is not essential for the development of undifferentiated cancers. The gene discussed is KRAS; the disease is cancer.