CREBBP and acute myeloid leukemia: To determine the ability of MYBMIM to dissociate the MYB:CBP/P300 complex in AML cells, we purified the MYB:CBP/P300 complex by immunoprecipitation using specific anti-MYB antibodies in the presence of 0 or 20 μM free MYBMIM, and determined its composition by western immunoblotting (Fig. 1f).