Used in research to study bone metabolism and immune regulation. Plays a key role in osteoclast differentiation and activation, making it valuable for investigating osteoporosis, rheumatoid arthritis, and bone metastasis. Employed in cell culture assays to stimulate osteoclast formation from precursor cells and to screen potential RANKL inhibitors for treating bone loss-related diseases. Also used in protein-protein interaction studies due to its binding affinity to RANK and osteoprotegerin. Serves as a standard for measuring RANKL levels in biological samples via ELISA or other protein analysis techniques. The Fc tag enables easy detection and purification, enhancing its utility in immunoassays and therapeutic development.