FN1 and neoplasm: In contrast to these reports, in the present study we have ruled out a role for exosomal fibronectin in mediating cell−exosome interactions and exosomal uptake, as the tumor Colo-320 cells (and the cell lines derived from them) appeared not to be able to biosynthesize fibronectin and because the exosomes produced by these cells did not bind exogenous fibronectin under the FBS-deprivation conditions employed throughout our study.