In our study, treatment with CAT decreased Ang II and AT1 as well as TGF-β/Smad2/3, indicating that CAT may attenuate the progression of BLM-induced lung fibrosis in mice partly by inhibiting phosphorylation of Smad2/3 via decreasing Ang II expression. The gene discussed is TGFB1; the disease is pulmonary fibrosis.