H2AX and leukemia: Treatment of CLL cells with EC-7072 resulted in a dose-dependent increase of the intracellular levels of active caspase-3 (Figures 3B,C) and heightened phosphorylation of histone H2AX (Figure 3D), which has been reported to constitute a cellular response triggered by caspase activation during apoptosis (35), suggesting that EC-7072 may promote leukemia cell death through a caspase-dependent pathway.