ROR1/TNFRSF21 protein level ratio in blood (OBA_2053154, an Ontology of Biological Attributes id) can be described as follows. A compound attribute that is the ratio of amount of inactive tyrosine-protein kinase transmembrane receptor ROR1 (human) in blood to amount of tumor necrosis factor receptor superfamily member 21 (human) in blood. Also known as: the ratio of amount of inactive tyrosine-protein kinase transmembrane receptor ROR1 (human) in blood to amount of tumor necrosis factor receptor superfamily member 21 (human) in blood.