Adipocytokine, or adipokine, is a general term for a bioactive product produced by adipose tissue. Adipocytokines include inflammatory mediators (IL-6, IL-8), angiogenic proteins (VEGF), and metabolic regulators (adiponectin; leptin). Although adipocytes can be induced to produce almost all known adipocytokines, preadipocytes, as well as macrophages and endothelial cells resident in adipose tissue, also contribute to adipocytokine production. Not all white adipose tissue is metabolically equivalent. Visceral adipose tissue, due in part to its association with the hepatic portal venous system, appears to be a critical regulator of glucose and fat metabolism. Subcutaneous adipose tissue, by contrast, is less understood. It appears to be the principal source of leptin and adiponectin. R&D Systems has a wide range of reagents for adipose tissue research. From proteins to ELISAs, R&D Systems manufactures and supports products necessary for both in vitro and in vivo metabolic research.