Angiogenesis is a necessary component of normal tissue repair, tumor growth and dissemination, and a wide variety of other inflammatory and pathological processes as well, including diabetic retinopathy, rheumatoid arthritis, and psoriasis. Consequently, the last two decades have seen extensive research into the regulation of neovascularization, particularly in tumors. Partly due to the emphasis on tumor angiogenesis, much of this effort has been devoted to the detection and characterization of angiogenic growth factors and inhibitory molecules. Thus assays have commonly been developed to measure the amount of vascular growth in vivo, or the modulation of endothelial cell (EC) proliferation, or migration in simple 2D culture systems (1 ).