FIGURE 5.

EGFR mediates TGF-β1-stimulated fibroblast proliferation, Akt, ERK, and Smad signaling, and α-SMA expression. A, NIH3T3 cells were stimulated with vehicle (−), TGF-β1 (+) alone or in combination with an EGFR inhibitor AG1478 (10 mm) for 48 h, and the effect of AG1478 on TGF-β-stimulated fibroblast cell proliferation was assessed by WST1 assay. B, cell lysates of NIH3T3 cells treated with vehicle (−), TGF-β (+) alone or combined with an EGFR inhibitor AG1478 for 16 h as indicated and activation (phosphorylation, p-) of Akt, ERK1/2 and Smad2/3, and α-SMA expression were evaluated by Western blot analysis. β-Tubulin was used as a loading control. Densitometry analysis was performed on Western blots from three individual experiments. C, immunocytochemical evaluation of α-SMA expression in NIH3T3 cells treated with TGF-β (+) alone and with the addition of an EGFR inhibitor AG1478. Values in A are mean ± S.E. (error bars) evaluations with three replicates and are representative of three separate experiments. B and C are illustrative of a minimum of three separate experiments. *, p ≤ 0.05.