CASP9 and leukemia: Mitochondrial matrix Ca2+ overload triggers cytochrome c release, caspase-9, and -3 activation, and leads to apoptosis.39, 40 Our results revealed that CJ-induced apoptosis, measured as caspase-9 and caspase-3/-7 activation and DNA degradation, was more pronounced in non-resistant Notch1 HD-mutant cells than in leukemia cells with extracellular juxtamembrane mutations in Notch1.