Induction of apoptosis by adaphostin or STI571 in K562 cells.

(A) Cells were treated for 24 hours with the indicated concentration of adaphostin (closed circles) or STI571 (open circles), sedimented, fixed, stained with Hoechst 33258, and examined for apoptotic morphologic changes. (B) Cells were treated for the indicated length of time with 10 μM adaphostin (closed circles) or 20 μM STI571 (open circles), sedimented, fixed, stained with Hoechst 33258, and examined for apoptotic morphologic changes. Cells analyzed in this panel correspond to samples blotted in Figures 3 and 4. (C) Cells were incubated for 24 hours with 20 μM STI571, sedimented at unit gravity, and incubated in drug-free medium for up to 48 more hours (open circles). Alternatively, cells were exposed to 5 μM continuously for the indicated length of time (closed circles). At the end of the incubation cells were fixed, stained, and examined for apoptotic morphologic changes. Results shown in each panel are from 1 of at least 3 representative experiments.