Antitumor cell activity of NSC-741909 is associated with ROS generation. (A) Two sensitive (H460 and H157 cells) and two resistant lung cancer cell lines (H322 and H1299) were treated with different concentrations of NSC-741909 (0.03 - 10 μM). Cell viability was determined 24 h after treatment. Cells treated with solvent (dimethylsulfoxide) alone were used as controls, and their viability was set to 100%. Each data point represents the mean ± SD of three independent experiments. (B) The five cell lines were treated with 1 μM NSC-741909 for 6 h and then stained with 2', 7'-dichlorofluorescein diacetate. Fluorescence intensity in cell samples was determined by flow cytometry analysis. Shown here are representative FACS graphs, which show the shift in the fluorescent cell population after NSC-741909 treatment (dark lines) when compared with control cells (light lines).