TNF and obesity due to melanocortin 4 receptor deficiency: Obesity induces the secretion of inflammatory cytokines in adipose tissue, such as MCP-1 and tumour necrosis factor-α (TNF-α) via activation of the ERK, nuclear factor-κB (NFκB), and c-Jun N-terminal kinase (JNK) pathways, which contribute to ephrin-B1 downregulation.