Effects of MK-801 on proplatelet formation, cell size, and cell number. (A) The number of proplatelet structures (arrowheads) was significantly reduced by the addition of 50 μM MK-801 (right panel), compared with the controls (left panel; quantified in panel B) (***P < .001, n = 60, mean of 3 independent experiments). (C) Cells treated with MK-801 were approximately half the size of the controls as demonstrated by image analysis of cell cytospin preparations (***P < .005, n = 300, mean of 2 independent experiments). (D) Addition of MK-801 has no significant effect on total cell number.