SMAD3 and pulmonary fibrosis: In gp130wt mice, however, ablation of Smad3 (Smad3−/−) reduced bleomycin-dependent lung fibrosis in mice as previously reported (Bonniaud et al, 2004; Zhao et al, 2002) when compared to the fibrotic lesions and excessive collagen deposition observed in Smad3 proficient wild-type mice 30 days after bleomycin challenge (Fig 4A and B).