Kinetics of expression of CD42 and CD62P (P-selectin) by CD34⁺CD41⁺ BM cells. At the times indicated, the cultures were harvested and stained simultaneously with anti-CD41, anti-CD42, and anti-CD62P. The stained cells were analyzed in a flow cytometer gating on CD41⁺ cells. The appearance of CD42 is shown on the left and the appearance of CD62P is shown on the right. The results are reported as the mean ± SD (n = 3 to 5) of the percentage of CD41⁺ cells expressing either CD42 or CD62P. (▪) TPO; (♦) TPO + IL-3; (▧) IL-3.