To determine whether the sensitizing effect of Olaparib to TRAIL-mediated apoptosis is restricted to this PARP inhibitor, we extended our analysis to another PARP-inhibitor, PJ34, and also analyzed the effects of specific siRNA-mediated suppression of PARP-1 on TRAIL-mediated apoptosis in GBM cells. Here, PARP1 is linked to glioblastoma.