In addition, high concentrations of NO produced by iNOS can generate free radicals, causing DNA damage.74 NO and iNOS activities induce apoptosis, angiogenesis, and DNA damage during tumorigenesis.75 NO increases the expression of matrix metalloproteinase and its inhibitor and promotes the progression of dysplastic lesions in BE to invasive carcinoma.72 These functional changes are essential because they identify the pathways that could be involved in promoting tumorigenesis. The gene discussed is NOS2; the disease is Barrett esophagus.