Firefly luciferase is one of the most utilized reporter genes for the study of gene expression. It is an extremely sensitive, rapid, and easy-to-use reporter gene. The chemiluminescent reaction catalyzed by luciferase is one of the most sensitive analytical tools for measuring gene expression. The luciferase substrate contains coenzyme A for increased and sustained luminescence compared to conventional methods. This eliminates the need for automated luminometer injection of the substrate and allows analysis by photographic film or scintillation counting. The lysis buffer contains polymyxin B which further enhances the signal and eliminates lysozyme treatment and freeze-thawing of cells. Cell lysis buffer is compatible with β-galactosidase assays. The enzyme encoded by the luciferase reporter gene catalyzes the oxidation of D-luciferin in the presence of ATP, oxygen, and Mg2+. The fluorescent product is quantified to measure its activity.