The CD39 Inhibitor Screening Assay Kit is a colorimetric assay designed to measure the activity of CD39 for screening and profiling applications. The kit comes in a convenient 96-well format with enough purified CD39 enzyme, ATP, CD39 assay buffer, and colorimetric detection reagent for 100 enzyme reactions. In addition, the kit includes the CD39 inhibitor POM-1 for use as an inhibitor control.