The ADAR1 Luciferase Reporter HEK293 cell line is designed to monitor RNA editing by Adenosine deaminase acting on RNA (ADAR1). This cell line stably expresses ADAR1 under the control of a CMV promoter and a separate ADAR editing reporter construct expressed under the control of another CMV promoter. The reporter contains the gene encoding firefly luciferase, which is constitutively expressed in the cells, upstream of the gene encoding the GluA2 ADAR substrate followed by the Renilla luciferase gene. The sequence corresponding to GluA2 has been modified to contain an amber stop codon (UAG). When edited by ADAR, this stop codon (UAG) will be changed to UIG (A to I edit), which is read as tryptophan (UGG) by the translation machinery. This edit allows translation to occur all the way to the end of the reporter mRNA and results in the expression of Renilla luciferase. Conversely, in the absence of ADAR1 activity, translation terminates at the stop codon and Renilla is not expressed. Reporter activity is read out as the Renilla Luciferase/Firefly luciferase ratio whereby inhibition of ADAR activity, and thus the UAG (stop) to UGG (tryptophan) conversion rate, will result in a dose-dependent decrease in the Renilla luciferase/Firefly luciferase ratio.