Figure 4

Effects of antioxidants on the bortezomib-induced cell death. Cells were treated with 50 nM bortezomib together with or without tiron for 24 hours, and production of ROS (A) and apoptotic cell (B) were analyzed. C, cells were pretreated with vehicle, GSH or NAC, sequentially treated with 50 nM bortezomib for additional 24 hours, and then intracellular GSH levels were measured. D, cells were treated as in C, and production of ROS was investigated. E, cells were treated as in C, and apoptotic cells were analyzed. *, P< 0.05; ** P < 0.001.