In obesity, pro-inflammatory cytokines, mainly interleukins IL-6, IL-1b and tumor necrosis factor α (TNF-α), are released and activate several serine kinases, including c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) [22,34,35]. Here, TNF is linked to obesity due to melanocortin 4 receptor deficiency.