We recently demonstrated that the adipose COX-2- macrophage migration inhibitory factor (MIF)-mediated inflammatory cycle between hypertrophic and hypoxic adipocytes, and macrophages, crucially contributes to the proinflammatory phenotypic switch of macrophages, via CD74, during the development of obesity-associated adipose tissue inflammation. The gene discussed is PTGS2; the disease is obesity due to melanocortin 4 receptor deficiency.