CCL2 and glioblastoma: Since radiated GBM cells release exosomal circ_0012381 which induces M2 polarization of microglia leading to better growth of GBM via the CCL2/CCR2 axis, Zhang et al. [142] suggested that inhibition of exosome secretion might represent a potential therapeutic strategy to improve the efficacy of radiotherapy in GBM patients.