in RA patients the count of CD34–THY1+ fibroblasts is threefold than that in OA, they generate a discrete perivascular zone, which surrounds the capillary structures in the synovium deep sublining layer, especially near aggregations of lymphocytes, and play an indispensable role in matrix infiltration, immune cell mobilization and osteoclast formation. The gene discussed is CD34; the disease is rheumatoid arthritis.