BCL2 and glioblastoma: siRNA knockdown of Mcl-1, Bcl-xL, and Bcl-2 further revealed that cleavage of PARP increased when combined with tunicamycin, particularly with Mcl-1 and Bcl-xL knockdown, suggesting that targeting these genes can synergize with ER-stress induction in GBM (Fig. 4G).