In a mixed BM chimera of DOX-induced MLL-AF9 transgenic and competitor WT cells expressing CD45.1, MLL-AF9 expression increased the frequency of AML cells and of myeloid cell subsets expressing NGFR, a reporter for MLL-AF9 (Figure 6—figure supplement 1B and C). Here, KMT2A is linked to acute myeloid leukemia.