PARP1 and glioblastoma: Stellettin B sensitizes GBM cells to PARP inhibitors (e.g., rucaparib and olaparib) by downregulating BRCA1/2 and RAD51, leading to synthetic lethality and tumor apoptosis.387 BET inhibitors, such as Birabresib, further enhance this effect by impairing DNA repair and disrupting cell cycle progression.