stimulatory and inhibitory signals. ALK1 (activin receptor like-kinase 1) is an endothelial-
specific type 1 receptor of the transforming growth factor-β receptor family. Heterozygotes
with mutations in the ALK1 gene develop hereditary hemorrhagic telangiectasia type 2
(HHT2). Recently, we reported that bone morphogenetic protein (BMP) 9 and BMP10 are
specific ligands for ALK1 that potently inhibit microvascular endothelial cell migration and …