Expression of VEGF receptors and hypoxic VEGF mRNA induction in tumor cells. (A) Protein expression of VEGFR1, VEGFR2 and NRP1 was determined in tumor cells and HUVECs under normoxia and after 24 hours of hypoxia with or without bevacizumab. Vinculin was used as a loading control. (B) Cell surface expression of VEGFR2 and NRP1 as analyzed by flow cytometry. Unstained cells cultured under normoxic conditions were used as a control. (C) Quantification of VEGFR2+ and NRP1+ cell surface expression. (D) Relative change of VEGFA mRNA expression under hypoxia versus normoxic controls. (E) Relative change of GLUT1 mRNA expression under hypoxia versus normoxic controls. n.d. = not done.