Glycophorin A, also known as CD235a, is a sialic acid glycoprotein located on the surface of human erythrocytes. It is a erythroid specific antigen. Its expression is accompanied by the whole process of erythropoiesis. Maintaining high expression on erythrocytes indicates that the erythrocytes are mature. Oncogenic nucleated erythrocytes in most erythroid derived leukemia express this protein, while acute myeloid leukemia and acute lymphoma leukemia almost do not express, which is a useful marker to identify erythroid differentiation in hematopoietic malignancies.