||This nuclear receptor assay system utilizes proprietary non-human cells engineered to provide constitutive high-level expression of full-length, unmodified human glucocorticoid receptor (NR3C1), a ligand-dependent transcription factor, commonly referred to as GR. The reporter cells include the luciferase reporter gene functionally linked to a GR-responsive promoter. Thus, quantifying changes in luciferase expression in the treated reporter cells provides a sensitive surrogate measure of the changes in GR activity. Luciferase gene expression occurs after ligand-bound GR undergoes nuclear translocation, DNA binding, recruitment and assembly of the co-activators and accessory factors required to form a functional transcription complex, culminating in expression of the reporter gene. Unlike some other cell-based assay strategies, the readout from The reporter cells demands the same orchestration of all intracellular molecular interactions and events that can be expected to occur in vivo. GR reporter cells are prepared using the proprietary CryoMite process. This cryopreservation method yields exceptional cell viability post-thaw, and provides the convenience of immediately dispensing healthy, division-competent reporter cells into assay plates. There is no need for cumbersome intermediate treatment steps such as spin-and-rinse of cells, viability determinations, cell titer adjustments, or the pre-incubation of reporter cells prior to assay setup. The nuclear receptor reporter assays are all-inclusive cell-based assay systems. In addition to GR reporter cells, this kit provides two optimized media for use during cell culture and in diluting the user"s test samples, a reference agonist, luciferase detection reagent, and a cell culture-ready assay plate.