KRAS and cancer: We detected 40 somatic mutations, including 10 mutations in genes recorded in the cancer gene list (Table EV1); primarily, we observed recurrent Notch1 (SNVs 5/10, indels 5/10) and KRas (SNVs 1/10) mutations (Table 1), consistent with Rosa26‐Lmo2 + Sca1‐Cre and human LMO2+ T‐ALL pathogenesis (Table 1).