Interestingly, we detected trapped PARP1-DNA complexes in U251 glioma cells, which did not meet our drug sensitivity criteria and also did not have enhanced sensitivity to the combination of olaparib with temozolomide, indicating that PARP-DNA complexes are not toxic to all cells (S7C and S7D Fig, compare lanes 6 and 10). This evidence concerns the gene PARP1 and central nervous system cancer.