When CHK2 was repressed by expression of an inactive dominant-negative CHK2 mutant or by exposure to specific chemical inhibitors, HCT116 colon cancer cells with DNA lesions entered mitosis and, in metaphase, underwent apoptosis (Castedo et al., 2004), a phenomenon called mitotic catastrophe (Castedo and Kroemer, 2004). Here, CHEK2 is linked to malignant colon neoplasm.