FIG. 6.

Insulin activates proteins in the insulin/IGF-I signaling pathway in control but not in βIRS2KO β-cells. Cells were stimulated with 100 nM insulin for 0, 1, 5, or 15 min. (a) Tyrosine phosphorylation of insulin receptor and IGF-1 receptor. (b) Tyrosine phosphorylation of IRS-1 and IRS-2. The immunoprecipitates (IP) with anti-IR, anti-IRS-1, or anti-IRS-2 antibodies from the indicated cell lysates with or without insulin stimulation were immunoblotted (IB) with anti-PY (top panels) or the p85 antibody (bottom panels). (c) PI3K activity associated with the phosphotyrosine complex. PI3K activity was measured in the immunoprecipitate with anti-PY from the indicated cell lysates. (d) Phosphorylation of Akt kinase and ERK. The cell lysates were immunoblotted with the indicated antibodies. Representative blots are shown from three independent experiments.