In an MLL-AF9-driven murine AML model, PD-L1 was expressed on Mac-1+/c-Kit+ LSCs at higher levels than on HSCs, and PD-L1 knockout leukemias were less aggressive in serial transplantations in lethally irradiated and thus immunodeficient mice. The gene discussed is KMT2A; the disease is acute myeloid leukemia.