Therefore, we analyzed the effect of the PPAR-β/δ agonist in TGF-β1-stimulated fibroblasts at the mRNA levels of all detectable MMPs. The mRNA levels of MMP1 in IPF fibroblast were increased (> fivefold) by the PPAR-β/δ agonist in comparison to TGF-β1 stimulation alone (Fig. 4H). This evidence concerns the gene PPARD and idiopathic pulmonary fibrosis.