Recently, Hauge S et al. reported that the p21 (a downstream target of p53)-deficient cancer cells are more sensitive to AZD1775 alone or in combination with ionizing radiation (Hauge et al., 2019), whereas both cell lines used in this study have been demonstrated to express p21 (Lin et al., 2017; Liu et al., 2018). Here, TP53 is linked to cancer.