Lysosomal-associated membrane protein 1 (LAMP-1), also known as CD107a, is a heavily glycosylated, type I transmembrane protein that constitutes the major sialoglycoproteins on lysosomal membranes. It is a ligand for galaptin, an S-type lectin present in extracellular matrix, through its recognition of acetyllactosamine oligosaccharide chains, and is a ligand for E-selectin-mediated cell adhesion. CD107a is expressed by granulocytes, T cells, macrophages, dendritic cells, activated platelets, tonsillar epithelium and some tumor cell lines, including U937 and KG1a. It is also a widely expressed intracellular antigen. LAMP-1 may function in protecting the inner surface of the lysosomal membrane by forming a barrier to lysosomal hydrolases. The upregulation of both CD107a and CD107b on the surface of tumor cell lines has been associated with their enhanced metastatic potential, where they may increase adhesion to extracellular matrix and endothelium (1-7).