As shown in Figure 5a, UP-ALL13 was very sensitive (half maximal inhibitory concentration, IC50 < 100 nM at 24 h) to the BET/BRD4 bromodomain inhibitor AZD5153, as compared to other common T-ALL cell lines harboring NOTCH1-activating mutations (DND41) or the rare t(7;9) translocation, leading to a constitutively active truncated membrane-bound form of NOTCH1 (CUTLL1; not shown). The gene discussed is BRD4; the disease is acute lymphoblastic leukemia.