CCL2 and peripheral nerve injury: Our research is the first comprehensive behavioral and biochemical study showing that many endogenous ligands of CCR1 (CCL2/3/5/7/8/9) and CCR3 (CCL5/7/8) are significant in the development (CCL2/3/5/7/8/9) and maintenance (CCL2/7/8) of neuropathic pain after peripheral nerve injury in mice.