Chemokine (C-X3-C motif) ligand 1 (CX3CL1), also known as fractalkine, is a macromolecular cytokine protein consisting of 373 amino acids and the only known member of the CX3C chemokine family. Soluble CX3CL1 is present in serum, urine, cerebrospinal fluid, amniotic fluid, and synovial fluid, and is expressed primarily by vascular endothelium, smooth muscle, neurons, and dendritic cells. Inflammatory cytokines such as TNF-α and IFN-γ induce most of the expression of CX3CL1.CX3CL1 exerts its adhesion and migration functions through interaction with the chemokine receptor CX3CR1. Soluble CX3XL1 strongly chemotaxis T cells and monocytes, whereas cell-bound chemokines promote strong adhesion of leukocytes to activated endothelial cells.CX3CL1 may be associated with antitumor activity and has an important role in abrogating normal inflammatory processes, such as wound healing.CX3CL1 is known to be a facilitator of the pathogenesis of certain conditions.