Figure 1. TGZ blocks TGFβ2-induced fibronectin expression in ARPE-19 cells.A: Time-course study of the effect of TGZ on the TGFβ2-induced fibronectin expression. ARPE-19 cells were either left untreated (UT) or were treated with 4 ng/ml TGFβ2, or were pretreated with 10 μM TGZ, 10 μM SB203580 (p38 MAPK inhibitor), or DMSO for 1 h and then exposed to TGFβ2 for the indicated time periods. Immunoblot results are from a representative experiment performed in triplicate with β-actin as loading control. B: Dose study of the effect of TGZ on TGFβ2-induced fibronectin expression. ARPE-19 cells were treated with different doses of TGFβ2 (1, 2, 4 ng/ml; lanes 2–4) for 48 h or pretreated with different doses of TGZ (1, 5, 10 μM; lanes 5–7) for 1 h before 4 ng/ml TGFβ2 treatment for additional 48 h. Immunoblot results are from a representative experiment performed in triplicate with β-actin as loading control. C: After densitometric scans of triplicate blots, values for fibronectin were normalized to β-actin. *p<0.05 versus 4 ng/ml TGFβ2-treated cells.