CD9 and glioblastoma: By comparing 15k EV‐ and 167k EV‐enriched proteins from all three GBM PDX cultures, we identified eight proteins (BAG3, MYADM, KRT13, 14, 16, 17, 19 and PTGFRN) in 15k EVs and six proteins (CD63, CD9, DIP2A, SLC44A1, SLC5A3 and SLC7A5) in 167k EVs that are common amongst all three GBM PDXs (Figure 3G).