CD81 and neoplasm: Furthermore, we previously observed with SP‐IRIS that both large and small EVs from human tumour tissue are double‐positive for CD63 and CD81 (Crescitelli et al., 2020), suggesting that there is no steric hindrance to identifying both CD63 and CD81 on the same EV, and we have no reason to believe that it would be different for serum and plasma EVs.