GO induces apoptosis and caspase 3 activation in sensitive cell lines. (A) The indicated cell lines were cultured in the presence or absence of 1000 ng/mL GO for 24 hours. DNA was then extracted and 1 μg run in a 2% agarose gel (lanes 2-4). As control, 100 ng DNA extracted from untreated HL-60 cells was also analyzed (lane 1). (B) The indicated cell lines were incubated with increasing concentrations of GO for 24 hours. Cytoplasmic extracts (50 μg) were analyzed by Western blotting with a procaspase 3–specific antibody, followed by a β-actin–specific antibody. The data are representative of at least 2 independent experiments. bp indicates base pair.