Surprisingly, other MYC-rearranged T-ALL cell lines (MOLT-16, SKW-3/KE-37), while reported to be relatively sensitive to the BET/BRD4 inhibitor JQ1 [8] (and Figure S3), resulted much more resistant to AZD5153 compared to UP-ALL13 at 24 h, much like the non-MYC translocated cell line DND41. Here, BRD4 is linked to acute lymphoblastic leukemia.