FIGURE 7.

IRS1/2 promotes cell proliferation. A, overexpression of IRS1/2 promotes Wnt3a-induced cell proliferation. 1 × 10³ MCF-7 cells stably expressing IRS1 or IRS2 were seeded in a 96-well plate. Cells were grown with or without Wnt3a conditioned medium. A₅₇₀/A₆₃₀ was measured to determine cell numbers. Data are presented as means ± S.D. (error bars). *, p < 0.05. The indicated proteins are shown by WB (right panels). B, depletion of IRS1/2 attenuates cell growth mediated by Wnt3a. MCF-7 cells stably expressing an shRNA against IRS1 or IRS2 were incubated with or without Wnt3a, and the numbers were determined by A₅₇₀/A₆₃₀. Data are presented as means ± S.D. NS, nonspecific shRNA as a control. The indicated proteins are shown by WB (right panels). C and D, depletion of Dvl2 impairs cell proliferation mediated by IRS1/2. Cell proliferation assay was performed using MCF-7 cells stably expressing IRS1 (C) or IRS2 (D) transfected with an shRNA against Dvl2. Data are presented as means ± S.D. The indicated proteins are shown by WB (right panels). E and F, IRS1/2-induced cell proliferation is impaired by depletion of Dvl2 with or without inhibition of PI3K/AKT signaling. Cell proliferation assays were performed using MCF-7 cells stably expressing IRS1/2 transfected with an shRNA against Dvl2. Cells were maintained with or without PI3K-specific inhibitor LY294002. Data are presented as means ± S.D. *, p < 0.05; **, p < 0.01.