Effect of vitamin C on caspase-10 activity. U937 cells were loaded with 13 mM vitamin C prior to FASL treatment (200 ng/mL) and lysed to determine activity of caspase-10. The results are presented as the percentage increase in caspase activity compared with cells without treatment and are the mean of triplicate samples. These results are representative of 2 independent experiments. Asterisk indicates a statistically significant difference (P = .033) in caspase-10 activity of cells loaded with vitamin C compared with control.