This MEF2D (phospho Ser444) ELISA Kit applies the qualitative technique of an indirect ELISA. Streptavidin is bound to the immunoassay plate and specific biotinylated double stranded (dsDNA) oligonucleotides are then added to bind to the streptavidin via a high affinity biotin-streptavidin interaction. After subsequent blocking of extraneous binding sites in each well, the sample containing the target of interest can be added. Primary antibody is added to bind activated transcription factors bound to the dsDNA oligonucleotide, which has been immobilized via the plate-coated streptavidin. A HRP-conjugated secondary antibody specific for rabbit IgGs is added, which allows for specific binding to the Primary Antibody, and consequently colorimetric detection upon addition of the TMB substrate. For color development, TMB (3, 3’, 5, 5’-Tetramethylbenzidine) is added to each well. After addition of the substrate, a peroxidase catalyzed reaction will produce a blue TMB Diimine product that is proportional to the target concentration in the sample. Color development is quenched by addition of Stop Solution, or 2 N Sulfuric Acid, which turns the solution yellow. The absorbance can then be read by a spectrophotometer at 450 nm and subsequently allowing for determination of the target concentration in the sample.