The RANK:RANKL TR-FRET Assay is designed to measure the inhibition of RANK binding to RANKL. This FRET-based assay requires no time-consuming washing steps, making it especially suitable for high throughput screening applications. The assay procedure is straightforward and simple; a sample containing biotinylated RANK, RANKL, anti-His Tb donor, dye-labeled acceptor, and an inhibitor is incubated for one hour. Then, the fluorescence intensity is measured using a fluorescence reader.