Vitamin C inhibits ROS generated by FAS-R ligation. (A) U937 cells were loaded with approximately 13 mM vitamin C prior to treatment with 1 μg/mL anti-FAS Ab for 3.5 hours and then stained with DCFH-DA to detect intracellular ROS by detection of dye fluorescence within 90 minutes by flow cytometry. (B) U937 cells were loaded with vitamin C, treated with 200 ng/mL FASL for 3 hours, and stained with DCFH-DA for 30 minutes for fluorescence measurement. The results are presented as the mean fluorescence intensity of DCFH-DA in arbitrary fluorescence units and are representative of 5 independent experiments.