Fig. 4. p90RSK did not affect C-terminal phosphorylation of Smad3 in response to TGF-β1. A: Human lung fibroblasts were treated with 10 µM FMK for 1 hour and then incubated with TGF-β1 (2 ng/ml) for 15, 30, or 60 minutes. Cell lysates were immunoblotted with antibodies of p-Smad3, Smad3, p-ERK1/2, ERK1/2, p-p90RSK, p90RSK, and tubulin. Bar graphs present the densitometric results of Western blot bands. ANOVA: *, p<0.05; **, p<0.01. B: Fibroblasts transduced with Ad-DN-RSK or Ad-Lacz were treated with TGF-β1 (2 ng/ml) for 15, 30, or 60 minutes, and cell lysates were immunoblotted using p-Smad3, Smad3, p-ERK1/2, ERK1/2, p90RSK, and tubulin antibodies. Bar graphs represent densitometric results of western blot bands. Results are presented as the means±SDs of three independent experiments. *, p<0.05; **, p<0.01 (n=3).