SOD2 and cancer: One of the important roles of reactive oxygen species (ROS) is regulating physiological signaling pathways to proliferate and differentiate.(8) Oncogenes, mitochondrial mutations, hypoxia, or tumor suppressor loss have been reported to induce production of mitochondrial ROS (mitROS) which involve tumorigenic signaling.(9) We have reported that the relation between mitROS and characteristics of cancer using a rat cancerous gastric mucosa cell-line (RGK1) and manganese superoxide dismutase (MnSOD)-overexpressed RGK cells, RGK-MnSOD.