Effects of antioxidants on ROS production and cell growth suppression induced by NSC-741909. Cells were treated with 1 μM NSC-741909 for 6 h (for ROS generation) or 24 h (for cell viability) in the presence or absence of different inhibitors. (A) After treatment, cells were stained with 2', 7'-dichlorofluorescein diacetate, and the fluorescent cell population was counted by flow cytometry and the relative ROS production was calculated. **p < 0.01, compared with cells treated with NSC-741909 alone. (B) Cell viability was determined using the sulforhodamine B assay. Cells treated with solvent (dimethylsulfoxide) alone were used as controls, with their viability set at 100%. Each data point represents the mean ± SD of three independent experiments. NAC, N-acetylcysteine; L-NAME, Nω-nitro-L-arginine methyl ester, a nitric-oxide synthase inhibitor; DSE, diallyl sulfide, an inhibitor of cytochrome P450 2E1; naproxen, cyclooxygenase inhibitor; oxypurinol, hypoxanthine/xanthine oxidase inhibitor; and NDGA, nordihydroguaiaretic acid, a lipoxygenase inhibitor.