Retinol binding protein (RBP) 4 is the only specific transport protein for vitamin A in the circulation whose function is to deliver vitamin to target tissues. In obesity and type 2 diabetes, expression of Glut4 is significantly impaired in adipocytes. Glucose transport via Glut4 is the rate-limiting step for glucose use by muscle and adipose tissue. Adipocyte-specific deletion of Gluts leads to notable elevation of RBP4 causing systemic insulin resistance, and that reduction of RBP4 improves insulin resistance. This identified a novel role of RBP4 in regulating insulin action and RBP4 is recorded as an adipocyte-derived hormone. The RBP4 (human) ELISA Kit is to be used for the in vitro quantitative determination of human RBP4 in biological fluids. This assay is a sandwich ELISA which utilizies a 96-well microtiter plate which was pre-coated with a monoclonal antibody and a purified polyclonal detection antibody. A HRP-conjugated anti-IgG, peroxidase and TMB (3,3',5,5'-tetramethylbenzidine) is added to generate a color intensity directly proportional to the concentration of RBP4 in the samples. This ELISA is specific for the measurement of natural and recombinant human RBP4. It does not cross-react with mouse RBP4, rat RBP4, human adiponectin, human resistin, human vaspin, human clusterin, human leptin, human IL-33, human GPX3, human progranulin, human FABP4, human ANGPTL3, human ANGPTL4, human ANG1, human ANG2, human Nampt, mouse Nampt. The assay range is 0.39-25ng RBP4/ml and a detection limit of 380pg/ml (based on adding 2 standard deviations to the mean value of the (50) zero standards).Sample Type:Cell and tissue culture supernatants, urine, plasma, serum, as well as many other biological fluids.Intended Use:For the in vitro quantitative determination of human RBP4 in biological fluids.Sensitivity:380pg/mlRange:0.39-25ng RBP4/mlSpecificity:MammalianTest Principle:This assay is a sandwich ELISA which utilizies a 96-well microtiter plate which was pre-coated with a monoclonal antibody and a purified polyclonal detection antibody. A HRP-conjugated anti-IgG, peroxidase and TMB (3,3',5,5'-tetramethylbenzidine) is added to generate a color intensity directly proportional to the concentration of RBP4 in the samples. This ELISA is specific for the measurement of natural and recombinant human RBP4. It does not cross-react with mouse RBP4, rat RBP4, human adiponectin, human resistin, human vaspin, human clusterin, human leptin, human IL-33, human GPX3, human progranulin, human FABP4, human ANGPTL3, human ANGPTL4, human ANG1, human ANG2, human Nampt, mouse Nampt.Kit Components:Pre-coated Microtiter Plate: 12x8 well stripsWash Buffer (10X): 1x50mlDiluent (5X):1x50mlDetection Antibody: 1x12mlDetector 100X (Hrp conjugated anti-IgG): 1x150ulHuman RBP4 Standard (lyophilized, 50ng): 1 vialHuman RBP4 QC Sample (lyophilized): 1 vialSubstrate Solution I (TMB): 1x6mlSubstrate Solution II (Peroxidase): 1x6mlStop Solution: 1x12mlPlate Sealers: 3 eachStorage and Stability:Store powder at 4°C liquid at -20°C. Store other components at 4°C. Stable for at least 6 months For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.