PARP1 and glioblastoma: The percent PARP1 positive area in both glioblastoma models was similar, with 42.0 ± 10.4 % and 41.5 ± 11.0 % for U251 MG and U87 MG, respectively (for healthy brain, PARP1 positive area was 2.7 ± 1.3 %).