Representative images showing the morphology of CD31-positive tubule-like structures obtained in response to either medium alone (Figure 2c), VEGF (Figure 2d), normoxic RA synovial cell supernatants (Figure 2e) or hypoxic RA synovial cell supernatants from the same patient (Figure 2f) are shown. The gene discussed is VEGFA; the disease is rheumatoid arthritis.