The Caspase-Glo 8 Assay is a homogeneous luminescent assay that measures caspase-8 activity. The assay provides a proluminogenic caspase-8 substrate in a buffer system optimized for caspase activity, luciferase activity and cell lysis. The addition of a single Caspase-Glo 8 Reagent in an add-mix-read format results in cell lysis, followed by caspase cleavage of the substrate and generation of a glow-type luminescent signal. The signal generated is proportional to the amount of caspase activity present. The Caspase-Glo Reagent relies on the properties of a proprietary thermostable luciferase (Ultra-Glo Recombinant Luciferase), which generates the stable glow-type luminescent signal and improves performance across a wide range of assay conditions. The system now includes a separate vial of a protease inhibitor, MG-132 Inhibitor, which may be used to reduce background, thus improving the performance of the Caspase-Glo 8 Assay in cell-based applications.