Thus, Sanyal et al. found that there was considerable staining for 3-NT in individuals with fatty liver or NASH (Sanyal et al., 2001), Laurent et al. showed that the concentrations of nitrites and nitrates were significantly increased in liver homogenates of ob/ob mice (Laurent et al., 2004), and we demonstrated that iNOS protein expression is upregulated in the liver of ob/ob mice (García-Ruiz et al., 2006). This evidence concerns the gene NOS2 and metabolic dysfunction-associated steatohepatitis.