Combined activation of PPAR-β/δ and PPAR-γ increased mRNA (Additional file: Fig. S4G) and protein levels (Fig. 5A) of PEX13 in TGF-β1-stimulated control and IPF fibroblasts compared to TGF-β1 treatment only. Here, TGFB1 is linked to idiopathic pulmonary fibrosis.