Many studies shown that TGEV infection could induce apoptosis in PK-15 cells, swine testicular (ST) cells, swine kidney cells, MDCK-APN cells (canine kidney cell line expressing porcine APN) or human rectal tumor cells (HRT18, expressing porcine APN) (Table 1) (74–82, 91), which associates with intracellular molecules, such as p53, reactive oxygen species (ROS), mitochondrial apoptosis-inducing factor (AIF), poly (ADP-ribose) polymerase (PARP), and caspases (74, 82). Here, ANPEP is linked to rectal neoplasm.