Chemokines, including C–C motif chemokine ligand 2 (CCL2), CCL3, and CCL5; C-X-C motif chemokine ligand 1 (CXCL1), CXCL5, CXCL6, CXCL9, CXCL10, CXCL11, CXCL12, and CXCL13; and C-X3-C motif chemokine ligand 1 (CX3CL1), contribute to RA pathogenesis via the recruitment of immune cells12–19. Here, CXCL12 is linked to rheumatoid arthritis.