OVER THE PAST 30 YEARS, THERE has been considerable interest in the elucidation of factors that mediate angiogenesis. These efforts led to the identification of factors such as vascular endothelial growth factor (VEGF), acidic and basic fibroblast growth factor (FGF-1 and -2), and angiopoietins, to name a few. Subsequent detailed investigations have revealed that finely tuned and precisely coordinated expression of these factors is critical for angiogenesis during both development and adult life. Failure to coordinate expression has significant implications, as excess angiogenesis can contribute to tumor growth and inflammatory disorders, whereas insufficient angiogenesis can contribute to ischemic heart disease or preeclampsia. More recently, additional factors, including Notch, Wnt, and morphogens such as bone morphogenetic proteins (BMPs), have emerged as critical regulators for proper blood vessel formation. BMPs, members of the transforming growth factor- (TGF-) superfamily, were originally identified as fac