Fig. 1. ABT-199&PIs synergize to induce cell death with concomitant induction of NOXA expression.

A–C SW982/WT and corresponding knock-out cell lines SW982/BAK^KO and SW982/BAX^KO were cultured for 24 h in presence or absence of 15 µM ABT-199 and/or 5 nM PI (BTZ, CFZ or IXZ). Apoptotic cell death was assessed by flow cytometric analysis of phosphatidyl serine exposure (Annexin V-APC) and relative mitochondrial membrane potential (TMRM). Reduced apoptosis in SW982/BAX^KO suggests BAX as relevant mediator of synergism, whereas BAK does not appear to play a major role in early (24 h) apoptosis induction. Graphs show mean and individual data points. Statistical significance was analyzed by an unpaired student´s t-test. D SW982/WT, SW982/BAK^KO and SW982/BAX^KO cells were incubated for 8 h in the presence or absence of 15 µM ABT-199 and/or 5 nM PI (BTZ, CFZ, IXZ; + 10 µM Q-VD-OPh). Expression of MCL-1, BCL-2, BAK, BAX, NOXA, and GAPDH (loading control) was analyzed by Western blot. Asterisks indicate identical Western blot due to cutting/reprobing. BTZ bortezomib, CFZ carfilzomib, IXZ ixazomib, CTRL control.