Used in immunological research to study Toll-like receptor 4 (TLR4) signaling pathways involved in innate immunity. Serves as a detection or purification tool in assays due to the Fc tag, enabling easy binding to protein A/G resins and detection with anti-Fc antibodies. Employed in protein-protein interaction studies, particularly in investigating ligand binding to TLR4, such as LPS from Gram-negative bacteria. Supports development of therapeutic agents targeting inflammatory diseases, sepsis, and autoimmune disorders by acting as a soluble receptor decoy or assay standard. Commonly used in ELISA, flow cytometry, and surface plasmon resonance (SPR) experiments.