ABCB1 and acute myeloid leukemia: We identified cases of relapsed or refractory AML from Manchester Cancer Research Centre’s Tissue Biobank with high ABCB1 expression by quantitative PCR (Figure 6A and Supplemental Table 4) and performed ChIP sequencing for H3K27Ac in high-expressing cases where sufficient cryopreserved bulk blast cells were available (red bars in Figure 6A).