We evaluated the relationship between mitochondrial ROS (mitROS) and HCP1 expression using rat gastric mucosal cells, RGM1, its cancer-like mutants, RGK1, obtained by treatment with carcinogenic chemicals, and manganese superoxide dismutase (MnSOD)-overexpressing RGK cells, RGK-MnSOD. This evidence concerns the gene SOD2 and cancer.