IL6 and rheumatoid arthritis: IL-6 induced tubule formation in a coculture system of human umbilical venous endothelial cells (HUVECs) and fibroblast-like synoviocytes from RA patients (RA-FLS) and that this angiogenesis was completely inhibited by anti-VEGF antibody, indicating that VEGF plays a crucial role in IL-6-induced angiogenesis [21].