CD321, also known as Junctional Adhesion Molecule A (JAM-A), JAM-1, or F11 Receptor, is a 32-40 kD type I transmembrane glycoprotein which belongs to the immunoglobin suerfamily. It is expressed broadly on leukocytes, platelets, erythrocytes, and epithelial and endothelial cells. CD321 plays a role in cell adhesion, leukocyte migration, and angiogenesis, through its interactions with integrins, such as LFA-1 and αvβ3 integrins.