Hao et al. reported that the tumor cell or dendritic cell-derived exosomes' capability of stimulating efficient T-cell responses is completely missed in diphtheria toxin (DT)-treated DT receptor transgenic mice with the host dendritic cell deficiency (52), highlighting that tumor exosomes need the host DCs for transfer of their stimulatory effect to CD8 CTL responses in vivo. This evidence concerns the gene CD8A and neoplasm.