G-protein-coupled receptors (GPCR) represent one of the most important classes of drug targets. Major G-protein families signal via second messengers like cAMP, which in turn, activate a range of effector systems to change cell behavior, gene transcription. Promega offers assays, such as the GloSensor™ cAMP Assay that can monitor second messenger activity, as well as sensitive reporter assays that can monitor activity of response elements or target genes.