In contrast, KLF4 overexpression either in vivo (transgenic mice) in unspecified cell types reduces bleomycin-induced lung fibrosis or in cultured human alveolar epithelial cells attenuates TGFβ1-induced downregulation of the epithelial marker E-cadherin and upregulation of fibronectin33. This evidence concerns the gene TGFB1 and pulmonary fibrosis.