Fig. 6.

IQGAP1 binds mTOR, regulates the cell size and requires mTOR for proliferation. (A) Left, endogenous IQGAP1 and mTOR reciprocally co-immunoprecipitate from untransfected HeLa cells. Mock denotes control immunoprecipitation with V5 antibodies. Right, exogenous V5-IQGAP1 and endogenous mTOR were co-immunoprecipitated with V5 antibodies from stable HeLa cell lysate and blotted with mTOR and V5 antibodies. (B) HeLa cells stably expressing IQGAP1 domains were seeded at 70% confluency, grown overnight to 80% and evaluated by FACS. The x-axis indicates relative cell size from equal numbers of cells in each cell line. The cell size distribution curve of the vector control, in solid grey, is included in each image for comparison. (C) IQGAP1 requires mTOR for proliferation. IQGAP1-C cells were untreated, treated with DMSO (the drug-vehicle as a control) or with 100 nM mTOR-inhibitor rapamycin, grown in low-serum medium and scored every other day for 6 days. Growth of vector-control cell (V) in low-serum was included for comparison. Means ± s.e.m. for n=3 experiments are shown (P≤0.001).