||This nuclear receptor assay system utilizes proprietary human cells engineered to provide constitutive, high-level expression of the full-length Human Progesterone Receptor (NR3C3), a ligand-dependent transcription factor commonly referred to as PGR. The reporter Cells include the luciferase reporter gene functionally linked to a PGRresponsive promoter. Thus, quantifying changes in luciferase expression in the treated reporter cells provides a sensitive surrogate measure of the changes in PGR activity.Luciferase gene expression occurs after ligand-bound PGR 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 target gene. Unlike in vitro binding assays, and 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. PGR Reporter Cells are prepared using the proprietary CryoMite process. This cryo-preservation 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 spinand-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 PGR Reporter Cells, this kit provides two optimized media for use during cell culture and in diluting the users test samples, a reference agonist, Luciferase Detection Reagent, and a cell culture-ready assay plate.