Moreover, increasing evidence supports a key role for BMP signaling angiogenesis and vasculogenesis in the lung [25, 26] . A large number of genetically modified mice with lesions in genes encoding either BMP ligands, receptors or antagonists exhibit defective angiogenesis. The importance of BMP signaling for the vascular system is demonstrated by the association of mutations in genes encoding for BMPRII and ALK1 with the development of two genetic vascular diseases, namely, pulmonary arterial hypertension and hereditary hemorrhagic telangiectasia.