Fig. 5.

Inactivation of MEK1 or MEK2 stimulates AKT phosphorylation. a, b Knockdown of MEK1 or MEK2 boosts AKT phosphorylation. Cells were transfected with scrambled siRNA, mek1 siRNA, or mek2 siRNA. After 48 h, cell lysates were subjected to western blot analysis. a Representative images are shown. b Densitometric quantification of phospho-AKT levels in (a). The ratio of phospho-AKT/GAPDH of transfection with scrambled siRNA is designated as 1. Data from three independent experiments were analyzed by one-sample t-test (mean ± SD; *P < 0.05). c, d Inhibition of MEK1/2 activation induces AKT phosphorylation. HCT116 cells were treated with 0, 1, 5, and 10 μM of U0126 for 72 h. The cell lysates were used to examine the levels of phospho-AKT. c Representative western blot images are shown. b Densitometric quantification of phospho-AKT and phospho-p70S6K1 levels in (c). The ratio of phospho-AKT/GAPDH or phospho-p70S6K1 in cells with 0 μM of U0126 is designated as 1. Data from three independent experiments were analyzed by one-sample t-test (mean ± SD; *P < 0.05; **P < 0.01)