Production of ROSs. Flow cytometric analysis was used to measure the formation of ROSs. Overlay histograms of ROS formation, as detected by DCF fluorescence, are shown in live cells treated for 5 hours with MGd and ascorbate (red lines) with 2 concentrations of MGd (50 μM and 100 μM, both with 100 μM ascorbate), mannitol control (black line), MGd control (green line), or ascorbate control (blue line) in (A) dexamethasone-sensitive C2E3 cells, (B) dexamethasone-resistant 1-310 cells, (C) chemotherapy-sensitive 8226-RPMI cells, and (D) highly chemotherapy-resistant DOX-10V cells. Dead cells were gated out with PI. A shift of the curve to the right represents increased ROSs (log scale). Absolute ROS mean fluorescence (MF) levels for each cell line are shown in associated legends. Tertiary butyl hydroperoxide was used as a positive control for each experiment (see “Materials and methods”). Data presented are representative of 3 independent experiments.