CASP3 and hepatocellular carcinoma: We found platelets profoundly reduced mitochondrial membrane potential of HCC cells (Fig. 5G, Fig. S6B), increased the proportion of apoptosis (Fig. 5H, Fig. S6C), and increased the level of cleaved caspase 3 in HCC cells (Fig. S7), suggesting that migrating platelets induce apoptosis of HCC cells.