CXCL8 and rheumatoid arthritis: In terms of a potential in vivo mechanism of action of RB200, angiogenesis is a key feature of RA [32], and indeed EGF has been reported to promote angiogenesis [30,31,33], in part through production of proangiogenic factors such as VEGF, IL-8 and basic fibroblast growth factor [13,30,34,35].