AKT1 and obesity due to melanocortin 4 receptor deficiency: This is in agreement with studies of other tissues that have shown that the S-nitrosylation of insulin signalling-associated molecules in muscle (e.g., IRS-1 and AKT) or key ER stress-associated molecules (e.g., unfolded protein response-UPR-regulator, IRE1α) in the liver can trigger insulin resistance and obesity [29,58,60,61].