KMT2A and acute myeloid leukemia: We then assessed whether the in vitro chemotherapeutic effects of Mettl3 deletion in BMMSCs would translate into a tumor response in vivo by intravenously injecting 2 × 105 MLL-AF9 AML cells into nonirradiated Prrx1-CreERT2;Mettl3fl/fl mice and Mettl3fl/fl mice to establish a systemic AML model.