THSD7A and cancer: The main findings of this study are (1) exosomes induce filopodia formation in both cancer cells and neurons and synapse formation in primary neurons; (2) endoglin and THSD7A are exosomal cargoes that promote filopodia formation; (3) endoglin regulates the levels of THSD7A in cancer cell SEVs and promotes cancer metastasis; (4) THSD7A is expressed by both cancer cells and neurons and directly induces filopodia formation, including in cells that cannot secrete exosomes due to genetic engineering.