The microplate provided in this kit has been pre-coated with an antibody specific to Bone Morphogenetic Protein 4 (BMP4). Standards or samples are then added to the appropriate microplate wells with a biotin-conjugated antibody specific to Bone Morphogenetic Protein 4 (BMP4). Next, Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then the mixture of substrate A and B is added to generate glow light emission kinetics. Upon plate development, the intensity of the emitted light is proportional to the Bone Morphogenetic Protein 4 (BMP4) level in the sample or standard.