Differential effects of AG957 and its quinone derivative NSC 676537. (A) Structures of adaphostin, the parent compound AG957, and NSC 676537, which is a quinone derivative of AG957. (B) K562 cells were treated with diluent, 30 μM AG957, or 30 μM NSC 676537 for 1.5 hours, then stained with CM-H₂DCFDA and examined by flow microfluorimetry to estimate peroxide levels. (C) K562 cells were treated for 24 hours with diluent, 30 μM AG957, or 30 μM NSC 676537; stained with PI; and examined by flow microfluorimetry for subdiploid cells. Error bars are mean ± SD of 3 experiments. ^*P < .05 relative to AG957. (D) K562 cells were incubated for 24 hours in the presence of the indicated agent, washed, and plated in 3% agar to determine clonogenic survival. (E) Peripheral blood mononuclear cells from a patient with CML were incubated with the indicated agent for 24 hours, washed, and assayed for granulocyte colonies as previously described.¹⁹  Similar results were obtained using cells from 2 additional patients with CML. (F) K562 cells were incubated in the presence of the indicated agent for 8 hours. Whole-cell lysates were probed with antibodies to c-abl or, as a loading control, procaspase-2.