FSTL1 and pulmonary fibrosis: Since NF-κB plays a key role in regulating the expression of FSTL1(Mattiotti et al., 2018; Hu et al., 2019; Yan et al., 2024), quercetin may downregulate FSTL1 expression to inhibit pulmonary fibrosis by inhibiting the NF-κB signaling pathway.