The 1D4B antibody recognizes CD107a which is also known as, Lysosome-Associated Membrane Protein 1 (LAMP-1). CD107a is one of the two major glycoproteins in lysosome membranes that provide useful markers to distinguish lysosomes from other organelles. CD107a may play a role in the lysosomal degradation of certain molecules. Mouse CD107a is a type I transmembrane glycoprotein. It consists of a 40-kDa core protein which is heavily glycosylated to form heterogeneous mature glycoprotein of 110-140 kDa. It is principally expressed in epithelial cells and macrophages in a variety of organs. Following activation, CD107a is relocated to the surface of some lymphocytes, macrophages, epithelial cells, endothelial cells, platelets, and tumor cells. Cell-surface CD107a may participate in intercellular adhesion and adhesion to the extracellular matrix. Cell surface CD107a expression can serve as a useful marker for cytotoxic NK and CD8+ T cells, as well as, some malignant tumor cells.