CD47(Integrin-Associated Protein,IAP) is a 40 - 60 kDa variably glycosylated atypical member of the immunoglobulin superfamily. The ubiquitously expressed CD47 binds to SIRP family members on macrophages, neutrophils, and T cells. CD47 is involved in the increase in intracellular calcium concentration that occurs upon cell adhesion to extracellular matrix. The protein is also a receptor for the C-terminal cell-binding domain of thrombospondin, and it may play a role in membrane transport and signal transduction. This protein has broad tissue distribution, and is reduced in expression on Rh erythrocytes.