After exposure to BLM for 28 days, notable pulmonary fibrosis was observed, and strong staining of Smad3, p-Smad3 and α-SMA in AECs was also revealed as a prominent feature of BLM-induced rat lung tissues compared to BLM-untreated or sham control tissues (Figure 3 C). This evidence concerns the gene ACTA1 and pulmonary fibrosis.