The MaxDiscovery™ Green Fluorescent Protein (GFP) ELISA Kit is an enzyme immunoassay that analyzes the quantity of Green Fluorescent Protein in cells, tissues or serum. Green Fluorescent Protein (GFP) is a 27 kDa protein derived from the jellyfish Aequorea victoria. It transduces blue chemiluminescence into green fluorescent light. Since the molecular cloning of GFP cDNA and the demonstration of GFP as a functional transgene, GFP has become a powerful tool with many applications in developmental, cell and molecular biology. GFP fluorescence is not species specific and can be expressed in bacteria, yeast, plant and mammalian cells. GFP can be fused with proteins of interest without interfering significantly with their assembly and function. GFP has been widely used as a reporter for gene expression, enabling researchers to visualize and localize GFP-tagged proteins within living cells without the need for chemical staining. Other applications of GFP include assessment of protein-protein interactions through the yeast two hybrid system and measurement of distance between proteins through fluorescence energy transfer (FRET) protocols. GFP is used to measure single cell metastasis and successful proliferation of stem cells. Although GFP expression can be easily detected under a fluorescence microscope, GFP fluorescence intensity varies from cell to cell due to heterogeneity in the nature of GFP expression. In order to quantitate the GFP expression in cells, FACS analysis is usually required, which is both expensive and time consuming. In response to these issues, Bioo Scientific has developed a highly sensitive ELISA assay which allows the researcher to directly measure the amount of GFP protein in cells, tissues and serum. Like most ELISA assays, the MaxDiscovery™ GFP ELISA Kit relies on Horseradish Peroxidase (HRP) conjugated secondary antibody and the (3,3´,5,5´-tetramethylbenzidine) TMB substrate. TMB is a chromogen that yields a blue color when oxidized with hydrogen peroxide (catalyzed by HRP) and has major absorbances at 370 nm and 652 nm. The color then changes to yellow with the addition of acid with maximum absorbance at 450 nm. The relative amount of GFP protein in the cells will be directly proportional to the amount of signal that is obtained at 450 nm.