CCL2 and cancer: Equally important, both in vitro co-culture and in vivo PNI models demonstrated that nerve cells, including Schwann cells and neurons, express CCL2 (C-C motif chemokine ligand 2) which capable of inducinge the migration of CCR2 (C-C Motif Chemokine receptor 2) expressing cancer cells toward these nerves, ultimately promoting PNI progression (16, 71, 72).