Contribution of VEGF to endothelial cell proliferation and tube formation induced by vIL-6. (A) HUVECs (2 × 10³or 4 × 10³ cells/well) were cultured for 72 hours with conditioned medium (1:2 dilution) from NIH3T3 (▪), BN7 (▩), and v6O (□) cells. The results represent the mean (±SD) of triplicate cultures; shown is one representative experiment of three performed. (B) HUVECs were cultured (2 × 10³ cells/well) for 72 hours with conditioned medium from v6O cells (1:2 dilution) alone or in conjunction with anti-VEGF Ab (2 μg/mL), anti–vIL-6 Ab (10 μg/mL), or control IgG (2 μg/mL). The results represent the mean (±SD) of triplicate cultures; shown is one representative experiment of three performed. (C) HUVECs (1 × 10⁴) were plated on Matrigel-coated wells in conditioned medium from v6O cells (1:2 dilution) supplemented with control IgG (2 μg/mL), anti-VEGF Ab (2 μg/mL), or anti–vIL-6 Ab (10 μg/mL). Photographs depict the microtubules after 24 hours of incubation (original magnification × 100).