Gene expression during tubule formation. (A) VEGFR2, (B) VE-cadherin and (C) CD31 mean expression in assayed EPCs and ECs, relative to 60% confluent ECs (± SEM; n = 3). Dotted line indicates expression in 60% confluent EPCs. Significant differences between cell types indicated (*P < 0.05, **P < 0.01). CytB expression in (D) EPCs and (E) ECs, relative to 0 h. Columns with different letters are significantly different (P < 0.05).