CCL2 and rheumatoid arthritis: Chemokines involved in monocyte recruitment, such as CCL2/MCP-1, CCL3/MIP-1α, and CCL5/RANTES, are readily detectable at the site of inflammation (96, 166), and blood monocytes from patients with RA express the corresponding chemokine receptors CCR1, CCR2, CCR3, and CCR5 (15).