Figure 3.

Time course and concentration dependence of H₂O₂-induced activation of caspase-9. HL-60 cells were stimulated for various periods of time (10–120 minutes) with 100 μM H₂O₂ (A) or for 120 minutes with increasing concentration of H₂O₂ (1 µM–1 mM) (B). Caspase-9 activity was estimated as described under “Material and Methods”. Values are presented as means ± SEM of 4–6 separate experiments and expressed as percentage above control (untreated samples). *p<0.05 compared to control values.