PEAR1/PECAM1 protein level ratio in blood (OBA_2053997, an Ontology of Biological Attributes term) can be described as follows. A compound attribute that is the ratio of amount of platelet endothelial aggregation receptor 1 (human) in blood to amount of platelet endothelial cell adhesion molecule (human) in blood. Also known as: the ratio of amount of platelet endothelial aggregation receptor 1 (human) in blood to amount of platelet endothelial cell adhesion molecule (human) in blood.