Our present study shows an additional potential interplay of STAT3 and PPARγ in renal fibrosis, as STAT3 was activated in kidneys of untreated TGF-β1 transgenic mice, but STAT3 activation was absent in kidneys of TGF-β1 transgenic mice chronically treated with pioglitazone. Here, TGFB1 is linked to renal fibrosis.