Activation of smad2/3 signaling pathway increased the expression of NOX4 in the endothelial cells, fibroblasts, human pulmonary artery smooth muscle cells and breast cancer cells [12-15] and activation of the smad2/3/NOX4/H2O2 signaling pathway had a positive role in cell proliferation and cell migration of endothelial cell [15]. The gene discussed is NOX4; the disease is breast cancer.