Sequential expression of IGF-1 and TGF-β was found to synergistically aggravate fibrosis, and upregulation of IGF-1 via TGF-β in myofibroblasts was documented in the fibrotic lung tissue in advanced idiopathic pulmonary fibrosis (IPF) [23]. This evidence concerns the gene TGFB1 and idiopathic pulmonary fibrosis.