FLNa and platelet biogenesis. (A) αIIbβ3/FLNa interaction after adhesion to fibrinogen is crucial to keep RhoA inactive, allowing actomyosin reorganization and proplatelet formation. (B) GPIbα–FLNa interaction stabilizes platelets and regulates the size under shear. It cannot be excluded that this interaction is necessary for the regulation of GPIb downstream effectors RhoA/Cdc42 during transendothelial platelet biogenesis.