Effect of BAH-1 on CD34⁺CD41⁺ cells. CD34⁺ CD41⁺cells were cultured under serum-free conditions in the presence of rhTPO, IL-3 (100 ng/mL), the optimal plateau concentration as determined for IL-3 with this assay, or various concentrations of BAH-1. On day 5, megakaryocytes in culture were quantitated visually by using an inverted microscope. *Statistically significant compared with PBS (P < .05).