AT101 sensitizes carcinoma cells to other BH3 mimetics. (A) HCT116 cells and (B) MiaPaca2 cells were incubated with either ABT-263, ABT-199 or A1155463 alone or in combination with 10 µM AT101 for 6 h. (C) HCT116 cells were transfected with non-targeting siRNA (siCtrl) or siRNA against NOXA (siNOXA) then incubated with either 5 µM A1155463, 10 µM AT101 or both for 6 h. Apoptosis was assessed by PARP cleavage and chromatin condensation, expressed as the percentage of surviving cells (n = 3, error bars represent standard deviation, ** p < 0.01). (D) HCT116 cells were incubated with 10 µM QVD for 1 h and then with A1155463 alone or in combination with 10 µM AT101 for 6 h.