CASP9 and chronic myelogenous leukemia, BCR-ABL1 positive: Caspase-8 was activated after 24 h of treatment in chronic myeloid leukemia cells (K562) with the AMP PaDef, whereas caspase-9 was not activated, suggesting that PaDef-induced apoptosis, which was related to caspase-8 activation, was primarily caused by the activation of exogenous signaling pathways [5].