CXCL12 and rheumatoid arthritis: In addition to this chemotactic activity, some chemokines (CCL2, CCL5, CCL18, CCL20, and CXCL12) increase the production of IL-6, CCL2, CXCL8, MMP-3, and COX-2 from FLS of patients with RA in vitro models (100, 115, 149, 150).