PARP1 and neoplasm: In both tumor cell lines, induction of single SAHA and synergistic SAHA- and TRAIL-induced apoptosis was accompanied by upregulation of the intrinsic apoptotic pathway verified by reduction of mitochondrial membrane potential, quantitative bivariate cytofluorometric analysis with Annexin V/propidium iodide, activation of effector caspases, and PARP cleavage.