HGF and rheumatoid arthritis: Indeed, a number of angiogenic factors, expression of which is triggered by the hypoxic and inflammatory environment within the arthritic joint [9,10], are abundant in RA synovial tissue, including vascular endothelial growth factor (VEGF) [8,11], angiopoietins [10,12], hepatocyte growth factor (HGF) [13] and fibroblast growth factor (FGF)-2 [14].