FAS and obesity due to melanocortin 4 receptor deficiency: Consistent with the significant accumulation of nSREBP-1c, both mouse models of obesity displayed significantly higher protein levels of the classical SREBP-1c-target lipogenic genes, including fatty acid synthase (FAS), stearoyl CoA desaturase 1 (SCD1) and acetyl CoA carboxylase 1 (ACC), in the liver as compared to wild-type controls (Fig 1C).