In contrast to the significant down-regulation of TGF-β1 in rosiglitazone treated PKD rat, TGF-β1 expression were not altered in rosiglitazone treated ADPKD cyst-lining epithelia in vitro(data not shown), which suggested rosiglitazone-mediated down-regulation of TGF-β1 in vivo were not through cyst-lining epithelia. Here, TGFB1 is linked to cyst.