EDN1 and obesity due to melanocortin 4 receptor deficiency: Given that obesity is characterized by adipocyte hypertrophy and hyperplasia in association with increased infiltration of immune cells and elevated secretion of proinflammatory cytokines and that the processes of adipocyte mitogenesis, adipogenesis, and adipokine secretion can be regulated by the ET-1/ET receptor system 12, 25, 27, 29, 36-39, elucidating the role of ET-1 signaling in adipose tissue expansion and dysfunction provides insights into the pathogenesis of obesity- and-adipokine-related metabolic disorders 29, 35.