Human HDAC8 is a class I HDAC and has been identified in a variety of human cancer tissues. Cayman’s HDAC8 Inhibitor Screening Assay provides a convenient fluorescence-based method for screening HDAC8 inhibitors. The procedure requires only two easy steps, both performed in the same microplate. In the first step, the substrate, which comprises the p53 sequence Arg-His-Lys-Lys(e-acetyl)-AMC, is incubated with human recombinant HDAC8. Deacetylation sensitizes the substrate such that treatment with the developer in the second step releases a fluorescent product. Fluorescence is then analyzed with an excitation wavelength between 350-360 nm and an emission wavelength between 450-465 nm.