Effect of NAC on bortezomib-induced apoptosis. CLL cells were pretreated with 10 mM NAC for 2 hours and then incubated with 20 nM bortezmib or 1 μM MG-132 for 12 hours. ΔΨm (A), annexin V (B), and ROS (C) were determined by flow cytometry. The conditions for the experiment were similar to those described in Figure 4.