Blocking anti–c-met antibody specifically inhibits the HGF-induced proliferation of HUVECs and HUVEC tubulogenesis in vitro. (A) Confluent (▵) or sparse (▴) HUVECs were treated for 96 hours with 25 ng/mL HGF in the presence of increasing concentrations of the anti–c-met H-190 antibody. Following incubation with the cell proliferation reagent WST-1, metabolically active cells were quantified by measuring the absorbance at 450 nm. White bar (□) indicates unstimulated control for confluent HUVECs; black bar (▪), unstimulated control for sparse HUVECs. Results are the mean values from triplicate cultures. (B) NHDFs were stimulated with 10 ng/mL PDGF BB, and hASMCs and DLD-1 cells were stimulated with 10% FBS, in the presence or absence of increasing concentrations of anti–c-met H-190 antibody. After 72 hours, proliferation was assessed by use of the cell proliferation reagent WST-1. Results are the mean values from triplicate cultures. Data are representative of 2 or more experiments. (C) HUVECs were cultured in 3-dimensional collagen in the presence of 20 μg/mL of either control rabbit IgG (left) or H-190 IgG (right). After 24 hours, only the cells in the control culture were reorganized into cords and tubes. In the presence of the H-190 antibody, the formation of cord network was blocked. Data are representative of 3 independent experiments. For all images in panel C: original magnification, × 200.