CD81 and cancer: In addition to small EV markers, e.g., exosome markers CD63, TSG101, and CD81, Ago2 proteins were detected in the P4 fraction of A549 cancer cell–conditioned media (Figs. 9A and EV5A), which contains small EVs measuring approximately 100 nm (Fig. EV5B), but not in the P3 fraction which contains large EVs (Fig. EV5B).