In order to study BETi resistance, we first ranked the IC50 values of JQ1, a well-known bromodomain inhibitor with high potency against BRD4, in a panel of cancer cell lines derived from leukemia (n = 26), including chronic myeloid leukemia (CML), T-lineage acute lymphoblastic leukemia (T-ALL), acute myeloid leukemia (AML), and erythroleukemia, based on the publicly available database PHARMACODB20 (Fig. 1a). Here, BRD4 is linked to acute lymphoblastic leukemia.