Glycophorin-A is a transmembrane protein present on the outer surface of normal human erythrocytes. In a normal erythrocyte, glycophorin-A is expressed through all stages of differentiation, from the normoblast stage to the mature erythrocyte. Once it is expressed to the maximum, the amount of glycophorin A in each red blood cell stays constant. Glycophorin A has also is also found in the blast cells of erythroleukemia cases.