Lymphocyte antigen 6G （Ly6G） is a 21-25 kDa glycosyolphosphatidylinositol-anchored protein that is predominatly expressed in granulocytes in bone marrow. Ly6G is a member of the so called Ly6/uPAR family of GPI-anchored surface proteins. Only encoded in mice, Ly6G shows structural and functional similarities to another Ly6/uPAR family member, CD177, which is expressed specifically on both human and mouse neutrophils. Ly6G is a homolog of the human CD177 protein, which has been shown to interact with cell adhesion molecules, and serves as a bona fide marker for neutrophils in mice. Ly6G contributes to the early engagement of intracellular pathogens by the immune system.