The present invention relates to the use of ligands for the FLK-1 receptor
for the modulation of angiogenesis and vasculogenesis. The invention is
based, in part, on the demonstration that Flk-1 tyrosine kinase receptor
expression is associated with endothelial cells and the identification of
vascular endothelial growth factor (VEGF) as the high affinity ligand of
Flk-1. These results indicate a major role for Flk-1 in the signaling
system during vasculogenesis and angiogenesis. Engineering of host cells
that express Flk-1 and truncated Flk-1 and the uses of expressed Flk-1 to
evaluate and screen for drugs and analogs of VEGF involved in Flk-1
modulation by either agonist or antagonist activities is described. The
invention also relates to the use of FLK-1 ligands, including VEGF
agonists and antagonists, in the treatment of disorders, including cancer,
by modulating vasculogenesis and angiogenesis.
