The activity of the MYC SE is highly dependent on the recruitment of transcriptional coactivators BRD4 and Mediator, which are most highly enriched at the MYC SE in MLL-AF9 AML cells and are co-enriched with p300 and p300-dependent H3K27Ac (Supplemental Fig. 9). Here, MYC is linked to acute myeloid leukemia.