CD81 and glioblastoma: 2024) (Figure 1B). 167k EVs were enriched for the canonical tetraspanin markers CD9, CD63 and CD81, whereas 15k EVs were enriched for Annexin A2 by western blot (Figure 1B). Surprisingly, NTA of 15k and 167k EVs prepared from the GBM PDX cell lines by ultracentrifugation pelleting revealed considerable amounts of approximately 150 nm diameter particles in the slower speed UC 15k EV preparations in addition to larger particles (Figure 1C). On the other hand, the 167k EV pellets contain mostly particles of peak diameters ranging between 142.5 and 149.5 nm (Figure 1C).