In human hepatoblastoma HepG2 cells, pancreatic carcinoma PANC-1 cells, colon carcinoma HT-29 cells, and breast carcinoma MCF-7 cells, hypoxia-induced ROS generation results in the downregulation of E-cadherin expression and an increase in the expression of N-cadherin. The gene discussed is CDH2; the disease is breast carcinoma.