MAPK8 and obesity due to melanocortin 4 receptor deficiency: Due to the specific heterogeneity of adipose tissue, macrophages in adipose tissue also activate c-Jun amino-terminal kinase (JNK) and nuclear factor-κB (NF-κB) signaling pathways through autocrine and paracrine, which affects the surrounding tissues and organs, forming a vicious circle and aggravating the occurrence and development of obesity.