Fig. 5

Caspase 3 is activated in β-lapachone-induced apoptotic cell death, but not in necrotic cell death. Cells were treated with DMSO or β-lapachone at 4 µM or 8 µM for 4 hr, followed by incubation in drug-free media for 20 hr. Cells were harvested and treated with the substrate, and intracellular caspase 3 activity was determined by flow cytometry as described in Materials and Methods.