Figure 2. Concentration dependence and time course for the inhibitory effect of R667 on TGF-β1-induced collagen gel contraction mediated by HTFs. Cells were cultured in collagen gels either for 3 days in the absence or presence of transforming growth factor-β1 (TGF-β1; 1 ng/ml) or vehicle (4 mM HCl containing 0.1% bovine serum albumin, BSA) and in the presence of the (A) indicated concentrations of R667 or for the indicated times with TGF-β1 (1 ng/ml) or vehicle in the absence or presence of R667 (1 µM; B). The extent of gel contraction was then determined. The extent of TGF-β1-induced gel contraction was 5.50±0.17 mm, 3.67±0.29, 2.83±0.29, and 2.43±0.12 mm in the presence of R667 at 0, 0.01, 0.1, or 1 µM, respectively (A). Data are means ± standard deviation (SD) of triplicates from experiments that were repeated a total of three times with similar results. *p<0.05 (the Tukey-Kramer test) versus the corresponding value for cells cultured with TGF-β1 alone.