Early support for this notion came from the demonstration that cells derived from human glioblastoma tissue secrete EVs in vitro [17], and the content of EVs in serum and cerebrospinal fluid (CSF) (e.g., presence of amplified epidermal growth factor receptor (EGFR) in EVs in CSF of glioblastoma patients [18]) differs between patients with and without glioma [17,18,19,20]. The gene discussed is EGFR; the disease is central nervous system cancer.