Effects of adaphostin on imatinib-resistant human Ph⁺ ALL cell lines. (A) The Ph⁺ ALL cell lines SUP-B15 (□), Z33 (▦), or Z119 (▪) were pretreated with either 24 mM NAC or 10 mM Trolox for 15 minutes and then exposed to 10 μM adaphostin as indicated. DNA fragmentation was assessed by PI staining and flow cytometry. (B) Z33R cells were generated as described in “Materials and methods” and exposed to indicated doses of adaphostin for 24 hours before DNA fragmentation was assessed as described in the legend to Figure 2. The increases in DNA fragmentation were statistically significant at 100 nM, 500 nM, 1 μM, and 2.5 μM doses of adaphostin according to the Student t test, with P values of .017, .016, .016, and .053, respectively. Error bars indicate SD.