The stromal cell- derived factor 1 (SDF1), also known as C-X-C motif chemokine 12 (CXCL12) and CXCL13 (also called BCA-1 or BLC) are B lymphocyte-specific chemokines, which act through their own specific receptors on the surface of B lymphocytes (CXCR4 and CXCR5, respectively), and cause the tissue gathering of B lymphocytes and the establishment of synovial germinal centers in RA(10). Here, CXCL13 is linked to rheumatoid arthritis.