Fractalkine (CX3CL1) is a unique chemokine belonging to the CX3C family, and is characterized by a C-X3-C cysteine motif within the chemokine domain, near the amino terminus of the protein (Bazan et al.). The chemokine domain is connected to an extended mucin-like stalk, followed by a transmembrane region, and a C-terminal intracellular domain (Imai et al.; Jones et al.). The protein signals through interaction with a single receptor, CX3CR1, expressed on monocytes, natural killer cells, T cells, microglia, and smooth muscle cells. Fractalkine is upregulated in endothelial cells by inflammatory signals and is synthesized as a membrane-bound molecule that mediates cell migration and adhesion (White and Greaves). Cleavage at the base of the stalk by metalloproteinases generates a soluble chemokine, which functions as a potent chemoattractant of target cells (Garton et al.; Apostolakis and Spandidos). Fractalkine has been implicated in pathology of inflammatory diseases, such as atherosclerosis and other vascular diseases, and has anti-apoptotic functions (White and Greaves).