Effect of rapamycin, wortmannin, and PD98059 on growth factor-stimulated MO7e colony formation. Factor-starved MO7e cells were pulse treated with rapamycin (20 ng/mL), wortmannin (10−7 mol/L), or PD098059 (50 μmol/L) for 1 hour, washed twice with culture medium, and plated in 0.3% agar in the presence of GM-CSF and SLF, as described in the Materials and Methods. After 7 days in culture, the colony number for each treatment group was assessed. Treatment of MO7e cells with GM-CSF in combination with SLF promoted growth of MO7e colonies, ranging from 60 to 170 colonies/plate. Colony numbers arising from MO7e cells pretreated with rapamycin, wortmannin, or PD098059 (*) were all significantly less than those treated with GM-CSF + SLF in the absence of inhibitors (P < .001). Rapamycin pretreatment yielded significantly less colonies in comparison to cells pretreated with PD098059 (**P < .05). Each experiment was conducted in triplicate. Each bar depicted represents the mean ± SEM colony number obtained from three individual experiments.
