Luciferase is a very sensitive genetic reporter. It catalyzes the bioluminescent oxidation of luciferin in the presence of ATP, magnesium and oxygen. Luciferase requires no posttranslational modification for enzyme activity. It is not toxic even at high concentrations (in vivo), and can be used in prokaryotic or eukaryotic cells since it. The reaction can be measured quantitatively after expression. Unlike other fluorescent reporters, uciferase has extremley high sensitviity and can be used for the assays that require demanding sensitivity.