While homeobox B7 (HOX B7) enhanced NHEJ efficiency in epithelial cells [14], caudal type homeobox 2 (CDX2) and thymocyte selection‐associated high‐mobility group box protein (TOX) inhibited the repair of broken ends in colon cancer [15] and leukaemia [16]. The gene discussed is CDX2; the disease is malignant colon neoplasm.