FIGURE 3.

Inhibition of mTOR kinase activity is necessary for rapamycin inhibition of GTPase expression. Rh30 cells infected with recombinant adenovirus expressing GFP or FLAG-tagged mTOR-T and mTOR-TE mutants were serum-starved for 24 h and then pretreated with or without rapamycin (100 ng/ml) for 2 h followed by stimulation with IGF-1 (10 ng/ml) for 22 h. Cells were harvested for Western blot analysis using indicated antibodies (A). Semiquantitative data for A by densitometry using NIH ImageJ are shown in B. Results are the means ± S.E. and are pooled from three independent experiments. ^a,p < 0.05, difference versus control group; ^b, p < 0.05, difference versus IGF-1 group (unpaired Student's t test).