SMAD2 and pulmonary fibrosis: The specific findings include: (1) TUDCA pretreatment inhibits BLM-induced pulmonary TGF-β/Smad2/3 signaling activation; (2) TUDCA pretreatment prevents the elevation of α-SMA and reversed the reduction of E-cadherin during BLM-induced lung fibrosis; (3) TUDCA alleviates BLM-evoked collagen deposition in the mice lungs.