To verify this notion, we re-introduced HA-tagged SELENBP1 in human colon cancer HCT116 p53 knockout cells (HCT116 p53−/−), and found that SELENBP1 still retained the ability to activate p21 expression even in the absence of p53 (Fig. 5d). This evidence concerns the gene CDKN1A and malignant colon neoplasm.