Genes encoding luciferase enzymes have been cloned from several species, including firefly and sea pansy [1] . Firefly luciferase catalyzes the oxidation of firefly luciferin, which produces a short-lived flash of light that decays within a few seconds. However, the sensitivity of the luciferase assay is significantly higher than the CAT assay [6] . The high sensitivity of luciferase-based bioluminescence assays is better suited to HTS platforms than CAT or β-Gal assays. Moreover, various luciferase substrates are available that have a long half-life and provide linear results over eight orders of magnitude [4] . The enzyme has also been used in a dual-luciferase reporter assay system, which allows both firefly and sea pansy luciferase reactions to be monitored independently in the same cell [7] . This enables the activation of two different signaling pathways to be measured simultaneously in response to the same stimulus.