CCR2 and osteoarthritis: For example, in an osteoarthritis model, C-C motif chemokine receptor 2 (Ccr2) signaling, a key driver of macrophage recruitment, is required for movement-provoked pain behaviors (19), and in mice prone to lupus (systemic lupus erythematosus), blocking macrophage colony stimulating factor (m-csf; a factor critical for macrophage recruitment and survival) can attenuate thermal hyperalgesia (20).