ViviRen™ Live Cell Substrate is a proprietary compound that generates Renilla luciferase luminescence from live cells under normal growth conditions. The substrate produces Renilla luciferase luminescence that is 3- to 5-fold brighter than coelenterazine in live cells. Low autoluminescence from the substrate permits signal-to-background ratios that are 100-fold higher than those for coelenterazine. ViviRen™ Substrate can be used in a variety of cell analysis techniques including reporter gene assays, RNA interference and bioluminescence resonance energy transfer (BRET), because the substrate permits real-time measurement in multiwell plates.