FIG. 5.

Induction of c-Jun by TGF-β is lost in Smad3 null fibroblasts. (A) Western blotting was performed by using nuclear lysates from Smad3^+/+ or Smad3^−/− primary MEFs treated with TGF-β1 for 0, 1, 2, or 4 h. MEFs were serum starved for 12 h in 0.2% serum before treatment. (B) The −79 to +170 reporter was transfected into Smad3^+/− or Smad3^−/− MEFs with empty expression vector (mock) or Smad3 expression vector (Smad3). Cells were treated with TGF-β1 for 24 h before harvesting for luciferase assays. Fold induction by TGF-β1 is indicated over the bars. (C) EMSA was performed by using the −18 to +170 probe and nuclear lysates from untreated Smad3^+/− MEFs or Smad3^−/− MEFs or cells of the same types treated with TGF-β1 for 1 h. The induced Smad3-Smad4 complex is indicated with an arrow.