MAPK8 and obesity due to melanocortin 4 receptor deficiency: These hypotheses could complement recent findings describing a participation of the NF-κB (nuclear factor ‘kappa-light-chain-enhancer' of activated B-cells) as well as the JNK (c-Jun N-terminal kinase) signaling pathway in the development of ER stress- and obesity-associated leptin resistance [34]–[36].