In bidirectional communication, brain endothelial cells release EVs containing tetraspanin CD9 to GBM [74], enhancing tumor progression through the inhibition of ubiquitination of IL6 receptor gp30 and promoting the activation of the signal transducer and activator of transcription 3 (STAT3) [75,76,77,78]. Here, STAT3 is linked to glioblastoma.