In summary, we established novel murine Cas9+ RUNX1-ETO9a cells with intact or deficient Trp53. These cells allow testing the effect of novel drugs in vitro and in vivo, enable genetic screens using sgRNA libraries, and will provide valuable information on the role of TP53 in the development of t(8;21) AML in future studies. The gene discussed is RUNX1; the disease is acute myeloid leukemia.