Summary: The Glucocorticoid Receptor Competitor Assay Kit, Red, provides a sensitive and efficient method for high-throughput, fluorescence polarization-based screening of potential glucocorticoid receptor (GR) ligands. The kit uses insect cell-expressed, human GR (also available separately) and a novel, high-affinity, fluorescent glucocorticoid ligand (GS Red) in a homogenous, mix-and-read assay format.