CXCR4 and rheumatoid arthritis: The results from the gene ontology analysis showed that gene expression of specific chemokines, chemokine receptors and those involved in chemokine activity, including CCL2, CXCL10, CXCL12, CCR2 and CXCR4, was significantly reduced by celastrol treatment in RA–FLSs, which is a novel finding.