Single BET inhibitors or copanlisib or bardoxolone methyl suppress ATL cell proliferation. (A) Immunoblot analysis of BATF3, c-MYC, p-AKT^S473, p-4EBP1, p-IκB-α, and p-NFκB-65 in 7 ATL cell lines and fibroblast cells. β-actin was used as a loading control. (B) Seven ATL cell lines were incubated with 1 μM of I-BET762 or copanlisib or bardoxolone methyl for 2 hours and 4 hours for p-IKKα. (C) HTLV-1 protein expression, Tax, and HBZ, in 7 ATL cell lines, Jurkat, and HuT102 cells. (D-F) Dose-response curves of I-BET762 (red), copanlisib (blue), or bardoxolone methyl (black) on ATL cell lines. Increasing concentrations (0 to 10 000 nM) of inhibitors were incubated with 10 000 ATL cells for 72 hours. The relative number of proliferating cells was analyzed by a thymidine incorporation assay. Results are representative of triplicate assays.