CXCL12 and rheumatoid arthritis: Patients with active synovitis had significantly higher serum levels of angiogenic biomarkers thought to be relevant to RA pathogenesis, including VEGF-D (P = 0.018), ANG-2 (P = 0.038), PlGF (P = 0.043), SDF-1 (P = 0.035), MMP-2 (P = 0.027) and bFGF (P = 0.007) (Table 2 and Figure 2).