Having verified that Kat2a deletion does not perturb normal hematopoiesis and thus preserves candidate progenitor cells-of-origin for leukemia transformation, we used a retroviral delivery system to express the MLL-AF9 leukemia fusion in progenitor-enriched, lineage-depleted (Lin-) WT and KO BM cells. Here, MLLT3 is linked to leukemia.