Induction of p53 upregulates the P21 or cyclin-dependent kinases inhibitor 1 A (CDKN1A), P21 inhibits the activity of cyclin D1 (CCND1) [57], and this finally controls cell cycle regulation, cellular senescence, and stem cell aging in colon cancer cells [58]. The gene discussed is CDKN1A; the disease is malignant colon neoplasm.