NOS2 and esophageal squamous cell carcinoma: Elevated tissue oxidative stress mediators such as reactive oxygen species (ROS) and reactive nitrogen species (RNS-iNOS and NO) in a chronic inflammatory state promote DNA double-strand breaks and genomic instability during the progression of esophageal squamous dysplasia and esophageal squamous cell carcinoma in human patients and mouse models11,17–19.