CASP9 and cholangiocarcinoma: It has been reported that several different types of genes regulated the mitochondrial-apoptosis in response to various stimuli.36 The released CYC subsequently activates caspase-9 that triggers effector caspase-3 and ultimately drives apoptosis.37–39 Much evidences indicated that many chemotherapeutic agents exerted apoptotic action via induction of ROS in CCA.26,38,40 In line with the above data, we found that WZ26 treatment increased caspase-3 activity in QBC-939-cells and xenograft tumors (Figure 5e-5g).