The rolling and adhesion of platelet-tumor cell emboli requires activation of endothelial cells, as shown by evidence that genetic depletion or pharmacological inhibition of P-selectin and vascular adhesion protein-1 (VAP-1) expression in endothelial cells dramatically hinders metastasis in different platelet-proficient in vivo models (83, 145, 165, 169, 170). This evidence concerns the gene AOC3 and neoplasm.