A number of evidences, including up-regulation of TGF-β signaling in glomeruli or tubulointerstitium in fibrotic kidney, kidney fibrosis-induced by increased TGF-β, and amelioration of kidney fibrosis by anti-TGF-β therapy, have demonstrated the direct TGF-β actions in fibrotic kidney diseases. The gene discussed is TGFB1; the disease is kidney disorder.