Expression profile of RUNX1, GATA-1, and CBFβ in primary CD34⁺human hematopoietic progenitors undergoing megakaryocytic and erythroid differentiation. Immunoblotting was performed on whole cell lysates with rabbit anti-RUNX1, mouse anti-CBFβ, rat anti–GATA-1 (N1), rabbit anti-gpIIb, rabbit anti–α-globin, and mouse antitubulin. Human CD34⁺ cells were grown in megakaryocytic or erythroid differentiation medium, and cells were harvested at the indicated durations. 1b and 1a refer to the AML1b and AML1a isoforms.