CD68 is a 110-kD transmembrane glycoprotein highly expressed by human monocytes, macrophages, and cells of the monocyte-macrophage lineage, such as osteoclasts and microglia. It is a member of the lysosomal/endosomal-associated membrane glycoprotein （LAMP） family and the scavenger receptor family. CD68 primarily localizes to lysosomes and endosomes, with a smaller fraction circulating to the cell surface. It plays a role in promoting phagocytosis and clearing cellular debris. The protein is also involved in mediating the recruitment and activation of macrophages.