Human RBP4 ELISA kit for the quantitative determination of human retinol binding protein 4.

Retinol binding protein 4 (RBP4), originally known as a specific transport of retinol in blood, is also a novel inflammatory and insulin resistance marker. Serum RBP4 levels are elevated in insulin-resistant mice and humans with obesity and type 2 diabetes. Animal experiments found that increased secretion of RBP4 might reduce insulin-dependent glucose uptake by muscle tissue by reducing the activity of PI(3)K (phosphoinositide 3-kinase), and increased hepatic glucose output by increasing the expression of the enzyme PEPCK. Studies suggested that elevated serum RBP4 was associated with components of the metabolic syndrome, including increased body-mass index, waist-to-hip ratio, serum triglyceride levels, and systolic blood pressure and decreased high-density lipoprotein cholesterol levels. Furthermore, circulating RBP4 concentrations were associated with subclinical cardiovascular disease, which imply that RBP4 could be involved in the development of atherosclerosis.