When αPD-L1 and tumor PD-L1 interactions were detected by a proximity ligation assay (PLA), we found that the PLA spots on tumor cells were obviously reduced by MC38-EVs but not MC38 Pdl1−/−-EVs (Fig. 3b), suggesting that MC38-EV PD-L1 and tumor PD-L1 competitively bound αPD-L1 in vivo. Here, CD274 is linked to neoplasm.