CCL2 and cancer: In preclinical models of chronic pain (for example, models of inflammatory, neuropathic, or cancer-related pain), several studies have clearly demonstrated that these CXCL12 and CCL2 chemokines and their receptors are upregulated by neuronal and non-neuronal cells (astrocytes, microglial cells, and infiltrating immune cells) throughout nociceptive neuroanatomical pathways [13,22].