IL6 and rheumatoid arthritis: VEGF protein and mRNA are expressed by synovial macrophages and synovial fibroblasts in the synovial tissues of RA patients, and cultured synovial cells are able to secrete VEGF under hypoxic conditions or when stimulated with IL-1, IL-6, IL-17, IL-18, -prostaglandin, or TGF-β, or by CD40 ligation [2–4, 15–17].