Among those, CD34–THY1+Cadherin-11± perivascular fibroblasts were greatly expanded in RA patients, exhibiting a proliferative, invasive, proinflammatory phenotype evident by the expression of migratory response genes such as CTHRC1, TWIST1, POSTN, LOXL2, PDGFRB and MMP14, transwell matrix invasion assays, and prominent in vitro secretion of IL-6, CXCL12 and CCL2 upon stimulation with recombinant TNF. This evidence concerns the gene CXCL12 and rheumatoid arthritis.