The PDE4D3 Assay Kit is designed for identification of inhibitors of PDE4D3 using fluorescence polarization. The assay is based on the binding of a fluorescent nucleotide monophosphate generated by PDE4D3 to the binding agent. The key to the PDE4D3 Assay Kit is the specific binding agent. Using this kit, only two simple steps on a microtiter plate are required for PDE4D3 reactions. First, the fluorescently labeled cAMP is incubated with a sample containing PDE4D3 for 1 hour. Second, a binding agent is added to the reaction mix to produce a change in fluorescent polarization that can then be measured using a fluorescence reader equipped for the measurement of fluorescence polarization.