ROS-induced cell death. The various MEL clones were treated with H₂O₂ for 20 minutes at room temperature and analyzed by FACS for viability (by propidium iodide) 48 hours later. Data are given in terms of units of fluorescence (= % dead cells) per total number of cells (live + dead) for one out of four independent experiments. ANOVA paired analysis for n = 4 set of data points at each H₂O₂ concentration were significantly different at P < .01 for all data analyzed.