Ontology of Biological Attributes id OBA_2053233 (REG4/SPINK4 protein level ratio in blood) can be described as follows. A compound attribute that is the ratio of amount of regenerating islet-derived protein 4 (human) in blood to amount of serine protease inhibitor Kazal-type 4 (human) in blood. Also known as: the ratio of amount of regenerating islet-derived protein 4 (human) in blood to amount of serine protease inhibitor Kazal-type 4 (human) in blood.