SMAD2 and pulmonary fibrosis: In conclusion, bleomycin-induced pulmonary fibrosis in rat models can activate the TGF-β/Smad2/3 and WNT/β-catenin pathways, and GA can have antifibrotic effects through the TGF-β/Smad2/3 and WNT/β-catenin pathways, although the change cannot be fully reversed.