Growth/differentiation factor 2 (Bone morphogenic protein 9, BMP9, GDF2) and Bone morphogenetic protein 10 (BMP10) bind with sub-nanomolar affinities to both the type I receptor Serine/threonine-protein kinase receptor R3 (ACVRL1, Activin receptor-like kinase 1, ALK1) and the type II receptor Activin receptor type-2B (ActR-IIB, ACVR2B) (Scharpfenecker et al. 2007, Laurent et al. 2007, Townson et al. 2012). BMP9 also bind with high affinity the type II receptors Bone morphogenetic protein receptor type-2 (BMPR2) and Activin receptor type-2A (ACVR2A, ActRIIA) (Kuo et al. 2014; Kienast et al. 2016). BMP9 binding leads to phosphorylation of Mothers against decapentaplegic homolog 1 (SMAD1), SMAD5 and SMAD8 in microvascular endothelial cells (David et al. 2007).
ACVRL1 is an important regulator of normal blood vessel development as well as pathological tumor angiogenesis (Massague 1998).