Quantitative chromatin immunoprecipitation assay demonstrated that stiff matrix significantly increased the constitutive enrichment of α6-promoter DNA in phospho c-Fos antibody-immunoprecipitated chromatin of IPF lung myofibroblasts at both the proximal (−2,873/−2,879 nt) and distal (−4,848/−4,854 nt) TRE sites (Fig. 1g). Here, FOS is linked to idiopathic pulmonary fibrosis.