By Western blotting, we discovered that Tenovin-6 induced a dose- and time-dependent specific cleavage of poly(ADP-ribose) polymerase (PARP), a hallmark of apoptosis, and a decrease in pro-caspase-3, the precursor form of caspase-3, in REH and NALM-6 ALL cells, indicating onset of apoptosis (Figure 4C). This evidence concerns the gene CASP3 and acute lymphoblastic leukemia.