“…VEGFR-1 mediates macrophage chemotaxis (Barleon et al, 1996) and the organization of the embryo vasculature by vasculogenesis (Fong et al, 1995), but not the definitive vessel assembly, which is closely dependent on VEGFR-2, a specific EC differentiation marker (Shalaby et al, 1999). The bFGF/ FGFRs system is mandatory for vasculogenesis, since it induces angioblasts to differentiate and assemble into initial vascular patterns (Gendron et al, 1996).…”