Glycophorin A is a molecule expressed by erythroid cells from the earliest morphologically recognizable erythroblast (arising just after the CFU-E stage) to the mature erythrocyte. Once glycophorin A is maximally expressed, the amount in each erythroid cell remains constant and does not appear to change during further maturation, despite the decreasing cell size. The majority of cases of erythroleukaemia express glycophorin A on the neoplastic erythroblasts. This antibody strongly stains normal erythroid cells at all stages of differentiation from the erythroblast to the mature red cell. The epitope recognized by this antibody is resistant to formalin fixation and paraffin embedding.