Moreover, in obesity there are elevated levels of several kinases such as protein kinase C isoforms, I Kappa B Kinase-β, and c-jun-terminal kinase, and these kinases have been implicated in alteration of insulin signaling by promoting serine phosphorylation of insulin receptor substrate which is associated with suppression of tyrosine phosphorylation of this substrate [166]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.