Summary: The Androgen Receptor Competitor Assay Kit, Red, provides a sensitive and efficient method for high-throughput, fluorescence polarization-based screening of potential androgen receptor (AR) ligands. The kit uses insect cell-expressed rat AR ligand binding domain tagged with glutathione-S-transferase (GST) and histidine (also available separately), plus a novel, high-affinity, fluorescent androgen receptor ligand (Fluormone AL Red) in a homogenous, mix-and-read assay format.