Mitocans synergize with ATO to promote apoptosis in the ATO-resistant cell lines. (A) Viability of NB4 and in-house–generated ATO-resistant cell lines to BH3 mimetics (n = 5). (B) Intracellular BH3 profiling of ATO-resistant and sensitive cells (n = 3) measured using intracellular cytochrome-c (Cyto-C) retention. (C) Viability of the sensitive and resistant APL and non-APL cell lines treated for 48 hours with OXPHOS uncoupler FCCP combined with ATO (ATO, 2 µM; FCCP, 10 µM; BH3 mimetics, 250 nM). All error bars represent the mean ± SEM of 4 independent experiments. *P ≤ .05; **P ≤ .01; ***P ≤ .001; ***P ≤ .0001. A1331852, BCL-XL inhibitor; ABT-199, venetoclax; CNTRL, control; S63845, MCL-1 inhibitor.