Fig. 2.

A: IGF-I rapidly induces Akt phosphorylation and activation. Akt is phosphorylated (p-Akt) on serine 473 within 5 min in response to treatment with 250 ng/ml IGF-I. Western blot analysis was performed on 30 μg of total cellular lysates prepared from primary isolated rat PTCs. B: IGF-I (250 ng/ml)-induced fibronectin (FN) expression is inhibited by chemical inhibitors of phosphatidylinositol 3-kinase (PI3K) (LY294002, 20 μM) or Akt (Akt inhibitor X, 2.5 μM). C: dominant negative Akt adenovirus (Ad-DN-Akt) abolishes IGF-I (250 ng/ml)-induced expression of fibronectin in PTCs. Adenovirus encoding GFP (Ad-GFP) was used as a control. Histograms represent the intensity of the fibronectin expression bands to the GAPDH band quantified by densitometry. Values are means ± SE (n = 3); increased **P < 0.01, or reduced compared with IGF-I induced, #P < 0.05.