CASP3 and intrahepatic cholangiocarcinoma: It was an ongoing process of ICC apoptosis in the normal colon tissue of healthy humans, and the apoptotic ICC could be identified by immunolabeling for activated caspase-3, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), and transmission electronic microscope for ultrastructural changes in the cells (Gibbons et al., 2009).