a. Effect of AA, NG, and their combination (CB) on TGF-β1(2ng/ml)-induced mRNA expression of Smad3, Smad7, and TGF-β1 by real-time PCR. b. Effect of AA, NG, and their combination (CB) on TGF-β1(2ng/ml)-induced protein levels of phospho-Smad3, Smad3, Smad7, and Smurf2 by Western blot analysis. Note that while AA inhibits phosphorylation of Smad3 by induction of Smad7, NG blocks Smad3 signaling by inhibiting Smad3 mRNA and protein expression. The combination of AA and NG additively inhibits TGF-β/Smad3 signaling. Data represent the mean ± SEM for at least 3 independent experiments. *p < 0.05, p < 0.01, ***p < 0.001 compared to the DMSO control. #p < 0.05, ##p < 0.01 compared to DMSO + TGF-β1 treatment.