CD107a, also known as lysosomal-associated membrane protein 1 (LAMP-1), is a heavily glycosylated, type I transmembrane protein that constitutes one of the two major sialoglycoproteins on lysosomal membranes that can be used to distinguish lysosomes from other organelles.1 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.2 CD107a is principally expressed in epithelial cells and macrophages in a variety of organs in normal and Beige mutant mice.3 LAMP-1 may function in protecting the inner surface of the lysosomal membrane by forming a barrier to lysosomal hydrolases.4