Flow cytometric analysis of expression of membrane proteins at cell surface at different stages of human terminal erythroid differentiation. The erythroblasts cultured for different days were stained with antibodies against the indicated proteins. The ordinate measures the number of cells displaying the fluorescent intensity given by the abscissa. Note progressive and dramatically increased expression of band 3 throughout terminal erythroid differentiation and decreased expression of α4 integrin during the late stage of terminal erythroid differentiation.