NOS2 and obesity due to melanocortin 4 receptor deficiency: The expression of iNOS, downstream from NFκB activation, was increased over 10 fold in the hepatocytes of HFD-fed mice (Fig 2B), in agreement with the iNOS-induced nitrosative stress in the pathogenesis of insulin resistance in an obese mouse model [38] and by the higher distribution of iNOS in the fatty liver of a HFD-induced obesity model [39].