cAng-1 is a positive regulator of SDF-1 expression in endothelial cells. (A) SDF-1 mRNA in HUVECs treated with cAng-1 (200 ng/mL; n = 4). (B) ELISA of SDF-1 protein in culture supernatants. HUVECs were treated with cAng-1 (200 ng/mL) during indicated time (n = 4, *P < .001, #P < .05). (C) HUVECs were incubated under 6 hours hypoxia with the indicated concentrations of cAng-1 and analyzed by ELISA. (n = 4, *P < .001, **P < .001). (D-E) Tie2 siRNA (siTie2) abolished the effect of cAng-1 (200 ng/mL) on SDF-1 expression under hypoxia. siCon indicates control siRNA (n = 3, *P < .001, **P < .005).