Under the influence of diabetic condition, a large amount of ROS generated inside mesangial cells stimulates the generation of ECM and inhibits its degradation via enhancing the expression of TGF-β to cause renal fibrosis [18, 19], because (1) ROS stimulates the activation of TGF-β/Smad pathway to accelerate the formation of renal fibrosis and (2) TGF-β activates Ang II to be responsible for renal fibrosis. The gene discussed is TGFB1; the disease is renal fibrosis.