CCL2 and idiopathic pulmonary fibrosis: A previous study revealed that TGF-β1 induces fibroblasts to produce CCL2, which can then induce further fibrotic responses in these cells, our result in Fig. 7l also shows that compared with healthy control, CCL2 expression level is higher in the fibroblast of IPF patients, indicating that the TGF-β pathway might be activated in IPF patients25.