The importance of CXCR4 expression in synovial membrane inflammation has been emphasised by the inhibition of collagen-induced arthritis by the CXCR4 antagonist T140, and by the finding of elevated CXCR4 gene expression in RA synovial biopsies with follicular-like lymphoid structures [4]. The gene discussed is CXCR4; the disease is Arthritis.