CASP9 and acute lymphoblastic leukemia: Similarly, evidence suggests that quercetin can also activate apoptosis through a mitochondrial pathway involving the activation of caspase-3 and caspase-9 and by the release of cytochrome c and cleavage of PARP in acute lymphoblastic leukemia (HPB-ALL and HL-60) and prostate cancer cells (DU-145 and PC-3) [54,55,56].