Ontology of Biological Attributes term OBA_2055780 (ACVRL1/TNFRSF9 protein level ratio in blood) can be described as follows. A compound attribute that is the ratio of amount of activin receptor type-1-like (human) in blood to amount of tumor necrosis factor receptor superfamily member 9 (human) in blood. Also known as: the ratio of amount of activin receptor type-1-like (human) in blood to amount of tumor necrosis factor receptor superfamily member 9 (human) in blood.