Fig. 4. PD suppresses TGF-β/Smad signaling pathway in pulmonary fibrosis. (A) Relative protein level of TGF-β, p-Smad2, Smad2, p-Smad3, Smad3 was detected by Western blot. (B–D) The ratios of TGF-β, p-Smad2/Smad2 and p-Smad3/Smad3 in different groups. All data were represented as the mean ± SD from three independent experiments. **P < 0.01 compared with control group, ^#P < 0.05, ^##P < 0.01 compared with TGF-β group.