Several DDR proteins, including ATM, ATR, and CHK1, are upregulated in GBM stem-like cells, rendering radiation resistance47 TTL-EV combined with radiation showed suppression of phosphorylated ATM, ATR, and CHEK1 protein expression, suggesting that it modulates the DDR signaling that mediates treatment resistance by promoting cell cycle arrest in GBM. This evidence concerns the gene CHEK1 and glioblastoma.