Effect of deferoxamine and desferrithiocin on iron/hydrogen peroxide–mediated DNA single-strand breaks. (A) Iron-loaded HepG2 cells were exposed to 0.33 mmol/L deferoxamine for 1 hour before exposure to 100 μmol/L hydrogen peroxide for 30 minutes. (B) Iron-loaded HepG2 cells were incubated with 0.67 mmol/L desferrithiocin before exposure to hydrogen peroxide. Shown are DNA strand breaks in control cells exposed to media alone, iron-loaded cells exposed to hydrogen peroxide, iron-loaded cells exposed to deferoxamine before exposure to hydrogen peroxide, and iron-loaded cells exposed to desferrithiocin before exposure to hydrogen peroxide. The results are the mean ± SEM of three experiments performed in duplicate (*P < .03 compared with iron-loaded cells exposed to hydrogen peroxide).