INS and obesity due to melanocortin 4 receptor deficiency: In obesity, the activation of the c-Jun N-terminal kinase (JNK) and nuclear factor κ B (NF-κ B) transduction signals is key in the inflammation process of adipose tissue and these pathways could interact with insulin signaling via serine/threonine inhibitory phosphorylation of IRS (Bastard et al., 2006; Gil et al., 2007).