Given that COX-2 expression in adipose tissue is also suppressed by obesity in humans and in rodents [39], the present study addresses the anti-obesity effect of COX-2 in adipocytes and demonstrates that adipocyte-derived PGE2 inhibits progenitor cell differentiation into white adipocyte and prevents the development of adiposity and obesity. The gene discussed is PTGS2; the disease is obesity due to melanocortin 4 receptor deficiency.