VWF and cancer: To test the hypothesis that VWF expression by cancer cells may also contribute to enhanced cancer cell-platelet aggregate formation and increased association of heteroaggregates with an endothelial monolayer, we incubated fluorescently labeled SAOS2 and KHOS cells (using CellTrackerTM Green) with freshly isolated platelets for 20 minutes prior to perfusion on a monolayer of HUVECs.