Employing a similar approach, we selected key endpoints involved in DNA damage sensing (ATM, ATR) and cell cycle markers (Histone H3) and checkpoint (CHK1, PLK1, WEE1) and measured their phosphorylated forms in GBM cells either left untreated or challenged with CPZ at IC30 for 8 h. The gene discussed is ATR; the disease is glioblastoma.