A recent in vivo study shows that tofacitinib 10 mg twice daily in MTX background downregulates the expression of MMP-1, MMP-3, CCL2, CXCL10, and CXCL13 in the synovium and the plasma levels of CXCL10 in RA patients during 28-day treatment [19]. Here, CXCL13 is linked to rheumatoid arthritis.