Pathway by which IGF-I induces phosphorylation of Akt, FKHRL1, p70S6 kinase, and GSK3β.

IGF-I induces phosphorylation of Akt, FKHRL1, p70S6 kinase, and GSK3β via the PI-3K pathway. H929 cells were cultured in serum-free medium for 16 hours and pretreated with increasing concentrations of the PI-3K inhibitor LY294002 (1 to 100 μM) prior to stimulation with IGF-I (100 ng/mL, 5 minutes). Cell lysates were analyzed as described in Figure 1with the use of antibodies indicated. The upper band (**) in panel B represents phosphorylated p85S6 kinase as described in Figure1.