Chan et al. reported that adipocyte COX-2/prostaglandin E2(PGE2)-mediated signaling involved in the development of obesity in vitro (3T3-L1 cells and human Simpson-Golabi-Behmel syndrome adipocytes), in vivo (high fat diet induced obesity rats and db/db mice) and human subjects [48]. The gene discussed is PTGS2; the disease is obesity due to melanocortin 4 receptor deficiency.