The JAK2 JH2 Pseudokinase Domain Inhibitor Screening Assay Kit is designed for screening and profiling small molecules that displace the fluorescently labeled probe (JH2 probe 1) from the JH2 domain of JAK2. The assay is based on the competition of the test compound with the JH2 probe for binding to purified JAK2 JH2. Using this kit, only one simple step on a microplate is required for screening. The JH2 probe 1 is incubated with a sample containing JAK2 JH2 to produce a change in fluorescent polarization. The FP signal is measured using a fluorescent microplate reader capable of measuring fluorescence polarization.