Stimulation of the PAFR increases the rate of megakaryocyte adhesion and spreading on immobilized fibrinogen. (A) Megakaryocytes were placed on immobilized fibrinogen for the designated times in the presence of 10 nM cPAF (bottom row), a stable PAF analog, or its vehicle (top row). β-Tubulin (white stain) was localized in the differentiated megakaryocytes. Scale bar represents 30 μm. (B-C) Megakaryocytes were pretreated with or without the PAFR blocker WEB 2086 (10 μM), and the cells were subsequently placed on immobilized fibrinogen in the presence of cPAF or its vehicle. The number of adherent megakaryocytes (B) or megakaryocytes with diameters greater than 30 μm (C) was determined for each time point. The figure is representative of 5 independent experiments. The bars in panels B and C represent the mean ± SD, and * identifies statistical significance (P < .05) between the treatment groups.