Effect of NMDA receptor inhibition on megakaryocyte differentiation. Flow cytometric histograms showing the effect of MK-801 treatment on expression of the megakaryocyte markers CD61 (top panel), CD41a (middle panel), and CD42a (bottom panel). TPO (25 μg/mL) and MK-801 (50 μM) were added at day 0 and day 7 and cells were cultured for a total of 14 days prior to analysis. Unfilled histogram indicates control; filled histogram indicates MK-801–treated. Events lying within a region set at 1% of the isotype control indicate positivity.