Halacli et al. [26], for example, demonstrated that the HCT116 cell line and its p53 knockout derivative (hereafter, HCT116p53−/−) exhibit comparable levels of apoptosis in response to ionizing radiation, and concluded that the radiation-induced apoptosis is p53-independent in this widely used colon carcinoma model. This evidence concerns the gene TP53 and colon carcinoma.