Fig. 7.
GSK-3–mediated S6K1 regulation controls cell proliferation. (A) Mouse fibroblasts growing in serum were treated with DMSO, SB415286, AR-A014418, or rapamycin for 2 d, after which cell numbers were counted. Data are the mean ± SEM of three separate experiments performed in triplicate. Results were statistically significant (*P < 0.01) by Student t test. (B) GSK-3α or GSK-3β knockdown cells were generated, and rate of proliferation was measured by counting cell numbers. Data are the mean ± SEM of three separate experiments performed in triplicate. Results were statistically significant (*P < 0.01) by Student t test. (C and D) Mouse fibroblasts stably expressing control or constitutively active (F5A-R3A-T389E) S6K1 were treated with DMSO, SB415286, or AR-A014418 for 2 d. Cells were lysed for immunoblot analysis (C) or cell proliferation rate was measured (D). Data are displayed as the mean ± SEM of three separate experiments performed in triplicate. Results were statistically significant (*P < 0.01) by Student t test.