RUNX1 and acute myeloid leukemia: However, and in contrast to the mouse models, the introduction of additional mutant oncoproteins, in this case KIT (N822K), NRAS (G12D) or mutant CBL into RUNX1‐ETO CD34+ PBSCs and CD34+ cord blood cells, still failed to initiate AML in immunodeficient mice, suggesting that even more additional cooperating factors are required or that cells need to undergo a strong selection in culture.73, 74, 75