In obesity, hepatocyte-derived DPP-4 activates inflammatory pathways in adipose tissue macrophages via the caveolin-1 and protease-activated receptor 2 pathways, leading to the activation of extracellular signal-regulated kinases 1 and 2 and nuclear factor kappa B (NF-κB) signaling [88] and promoting the release of pro-inflammatory mediators including cytokines, chemokines, and neuropeptides [89]. The gene discussed is DPP4; the disease is obesity due to melanocortin 4 receptor deficiency.