Firefly luciferase has been used as a sensitive reporter for studying gene regulation and function. Luciferase provides a 1000-fold increase in sensitivity in comparison to the standard chloramphenicol acetyltransferase (CAT) assay. Firefly luciferase catalyzes the oxidative carboxylation of luciferin, a reaction with the highest efficiency of any known bioluminescence reaction. The light emission from the reaction can be recorded using a luminometer. Assay Genie's Luciferase Reporter Assay Kit provides a simple means for detecting luciferase activity in transfected eukaryotic cells. For measurement of expressed luciferase in vitro, luciferase is first extracted from transfected cells through cell lysis. Then CoA, ATP, Mg²and buffer are added to the lysate (Inclusion of CoA yields a nearly constant light emission rather than typical flash Kinetics). The luminescent reaction is then triggered by an injection of luciferin, and the emitted light is recorded by a luminometer. By providing CoA, along with ATP, Mg² in an optimized buffer solution, Assay Genie's Luciferase Reporter Assay Kit ensure maximal sensitivity, consistent light output, as well as convenience and consistency when working with multiple samples.