In order to further analyze the relationship between AP-1 and TGF-β1 or TREM-1 in pulmonary fibrosis, Pearson Correlation analysis was performed, and the results showed that the AP-1 mRNA expression was positively related to TGF-β1 mRNA expression (r = 0.713, p < 0.05) (Fig. 4b) and TREM-1 mRNA expression (r = 0.906, p < 0.05) (Fig. 4c), respectively. Here, FOS is linked to pulmonary fibrosis.