Overexpression of B55gamma in Glioma cells inhibits the phosphorylation of S6K. A. Overexpression of B55gamma in U251 decreases phosphorylation of S6K, but phosphorylation of 4EBP1 and mTOR and AKT have no significant change. B. U251 cells were transfected with control vector or B55gamma alone or B55gamma + S6K WT or B55gamma + S6K KA for 48 hrs. Cell viability assays were performed under the treatments of Rapamycin at 15 nM and 50 nM, DMSO treatment was control. C. Transfection of S6K WT and S6K KA into U251V and U251B55gamma cells followed by the measurements of cell viabilities under the glucose withdrawal for 24 hrs. Columns, mean of three independent experiments; bars, SE. **, P < 0.01; ***, P < 0.001.