To demonstrate a causal relationship between the presence of IL-17 producing cells within the joint and VEGF-A production, we cultured synovial fibroblasts (a known source of VEGF-A [26]) from 6 patients with RA with rIL-17 and measured secreted VEGF-A (Fig. 5D). The gene discussed is VEGFA; the disease is rheumatoid arthritis.