Platelet-endothelial cell interaction from the viewpoint of sphingolipids. Platelets incorporate Sph and release Sph-1-P in a protein kinase C (PKC)-dependent manner. Sph acts as an inducer of endothelial cell apoptosis, whereas Sph-1-P acts as a survival factor. This may be one of the mechanisms by which platelets maintain the integrity of endothelial cells.