Fig. 9.

Magnitude of IGF-I-induced tyrosine phosphorylation of IGF-IR, IRS-2, and Shc in IRS-1^+/+ (●) and IRS-1^−/− (○) myofibroblasts. Intestinal myofibroblasts from IRS-1^+/+ and IRS-1^−/− mice were serum starved and were treated with IGF-I at different doses. Cell extracts were immunoprecipitated with antibodies against IGF-IR, IRS-2, or Shc and were immunoblotted with anti-phosphotyrosine antibodies or antibodies to total protein. Data points represent fold increases in tyrosine-phosphorylated protein vs. zero dose of IGF-I. Each data point represents a mean ± SE; n ≥ 4 independent experiments. ^aP < 0.05 in IRS-1^−/− cells vs. IRS-1^+/+ cells.