BRD4 and leukemia: Upon dual inhibition of BRD4 and CDK7 using the combination of I-BET151 and THZ1, we observed a strong synergistic lethality in K562 and Jurkat leukemia cells (Fig. 2a, b), but not in OCI-AML2 cells that are highly sensitive to BETi (IC50 = 160 nM)20 (Supplementary Fig. 3a).