MAPK8 and obesity due to melanocortin 4 receptor deficiency: In addition, there is evidence implicating the serine kinases c-Jun Kinase (JNK) and inhibitor of NF-κB kinase (IKK) in cytokine-dependent IR: obesity is associated with increased JNK activity in adipose and liver tissues [41] and mice lacking IKK-β are resistant to obesity-induced IR [42].