Angiogenesis is the formation of new blood vessels from existing blood system. Tumors promote their own vascularization. The understanding of the mechanisms that regulate angiogenesis and the identication of the key molecules involved should allow to identify new therapeutic targets in order to combat and control angiogenesis and therefore cancer. Such a molecule that inhibits the neo-angiogenesis was characterized in our laboratory. This molecule, BMP9, therefore represents an important tool in the pathologies where angiogenesis is implicated as in the cancer.