PEITC killed CLL cells mediated by glutathione depletion of ROS stress. (A) Time course of CLL cell killing by 5 μM PEITC, analyzed by annexin-PI assay. Representative dot plots (left panel) and quantitation of cell death (right panel) are shown. Percentage of drug-induced cell death was calculated by subtracting the spontaneous cell death from the overall cell death in the PEITC-treated sample. Each bar represents the mean and 95% CI (n = 23). (B) Depletion of cellular glutathione in CLL cells after exposure to 5 μM PEITC for indicated times. Each bar represents the mean and 95% CI (n = 9 CLL samples for each time point). (C) Effect of NAC on PEITC-induced glutathione depletion. CLL cells were preincubated with 1 mM NAC for 1 hour before exposure to 5 μM PEITC for 5 hours. Each bar represents the mean and 95% CI (n = 4). (D) Effect of NAC on PEITC-induced ROS accumulation is shown. CLL cells were preincubated with 1 mM NAC for 1 hour before exposure to 5 μM PEITC for 2 hours. Each bar represents the mean and 95% CI from assays of 3 different CLL samples. (E) Effect of NAC on PEITC-induced cell death. CLL cells were pre-incubated with 1 mM NAC for 1 hour before exposure to 5 μM PEITC for 24 hours. Cell death was detected by annexin/PI assay. Each bar represents the mean and 95% CI from assays of 7 CLL samples.