Expression of glycoprotein IIb/IIIa by CD34⁺ MNC after 10 day exposure to TPO + KL + IL-3 (A); TPO + KL + IL-3 + IL-11 + IL-6 (B); TPO + IL-3 + IL-11 + IL-6 (C); and TPO + KL + IL-3 + IL-11 + IL-6 + IL-1α (D). Cells displayed in upper panels of A, B, C, and D were cultured in Iscove DMEM supplemented with 25% animal serum (12.5% BCS + 12.5% HS), whereas cells displayed in lower panels of A, B, C, and D were cultured in Iscove DMEM supplemented with 25% serum substitute. Representative data from three independent studies are shown.