HSP90B1 and central nervous system cancer: Western blotting showed the expression of Grp94 in the cell lysates, while no expression of this protein was observed in the EVs extracted from the cells, confirming the validity of Grp94 as a negative control (Figure S5B).These results, together with the flow cytometry analysis, demonstrated that EGFR in EVs could accurately show the expression of EGFR in the parental cells, and the expression level of EGFR was significantly higher in the glioma cells than in the normal cells, suggesting that EGFR in EVs could be taken as a candidate diagnostic marker for glioma.