Chemokines are a superfamily of low molecular weight cytokines that were initially described based on their ability to induce the directed migration of leukocytes to sites of inflammation or injury. In humans, there are approximately 45 chemokines that bind to 19 G-protein-coupled receptors. In addition to mediating cellular migration, chemokines have now been shown to affect many cellular functions including survival, adhesion, invasion, proliferation, and to regulate circulating chemokine levels. Although chemokine receptors were first described on leukocytes, it is now appreciated that...