CXCL12 and rheumatoid arthritis: In a recent report, it was shown that the HMGB1/CXCL12 heterocomplex can be maintained in rheumatoid arthritis (RA) by the activity of the prostaglandin E2 (PGE2)/COX2 pathway, the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, and the thioredoxin system, all of which are associated with the activation of the disease (14).