STAG2 deficient glioblastoma and Ewing sarcoma cells are more sensitive to DNA alkylating agents, DNA crosslinking agents, topoisomerase inhibitors, Poly (ADP-ribose) polymerase (PARP) inhibitors, and ataxia telangiectasia and Rad3-related protein (ATR) inhibitors [16, 17]. This evidence concerns the gene ATR and Ewing sarcoma.