Ly6G (Lymphocyte antigen 6 complex locus G6D) is a 21-25 kDa glycosylphosphatidylinositol (GPI)-anchored protein that belongs to the Ly-6 superfamily and is expressed in a developmentally regulated manner by myeloid cells, including neutrophils, granulocytes, and some monocytes. It serves as a key marker for mature neutrophils and is widely used in research to identify and deplete these cells in vivo. Ly6G is transiently expressed on monocytes during bone marrow development, while its expression on granulocytes and peripheral neutrophils correlates with their differentiation and maturation levels. This antigen plays important roles in immune responses, such as antitumor immunity and neutrophil-mediated inflammation.