Effect of adaphostin or STI571 on colony-forming ability of K562 cells.

(A) Log-phase cells were exposed to the indicated concentration of adaphostin or STI571 for 24 hours, washed, and plated in soft agar. Colony formation was examined 10 to 14 days later. (B) cells were exposed to the indicated concentrations of STI571 for 24, 48, or 72 hours, washed, and plated in soft agar. Results shown are representative of 7 to 17 (A) or 5 (B) experiments. Error bars, mean ± 1 SD from quadruplicate plates treated with the indicated drug concentration in the experiments presented.