Rapamycin did not inhibit the synthesis of c-Myc in MO7e and F36P cells. (A) Elutriated G₁-arrested cells were pretreated with diluent (dimethyl sulfoxide [DMSO]) or 25, 250, and 2500 nM rapamycin for 30 minutes at 37°C and were then incubated with 10 ng/mL (MO7e) or 1 ng/mL (F36P) GM-CSF for 2 hours at 37°C. (B) Elutriated G₁-arrested cells were pretreated with diluent (DMSO) or 250 nM rapamycin for 30 minutes at 37°C and were then incubated with 10 ng/mL (MO7e) or 1 ng/mL (F36P) IL-3 for 2 hours at 37°C. Total cell lysates (3 × 10⁵ cells per lane) were separated by SDS-PAGE and immunoblotted. Western blotting for p70^S6K was initially done using antiphosphorylated form-specific antibody followed by stripping and reblotting by antitotal p70^S6K antibody. These show the representative results of 3 independent experiments.