A molecule on the surface of a cell that serves as a homing device to direct another molecule to a specific location. [address, fr. O.Fr. adresser, to direct, fr. L.L. addirectiare, fr. L. ad, to, + directus, straight, direct, + -in]
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ad·dress·in (ə-dresґin) a molecule on the surface of vascular endothelial cells that mediates the attachment of specific leukocytes, particularly lymphocytes, to the endothelium, binding with their homing receptors.Medical dictionary. 2011.