MAPK1 and obesity due to melanocortin 4 receptor deficiency: The HFD-induced obesity-related proteins showed significant enrichment in the expected pathways, such as Hypoxia-Inducible Factor (HIF)1α signaling, extracellular-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling, the production of NO and ROS in macrophages, the sirtuin signaling pathway, and the apelin adipocyte signaling pathway (Figure 5A).