Senescence serves as a tumor-suppressor mechanism, but key regulators of senescence, such as p16INK4a, p21CIP1, p53, and H3K9me3, also impact stem cell functions, or “stemness.” Recent studies have shown that senescence can drive cancer cells towards stemness, promoting cancer stem cell regeneration (114, 371–376). Here, CDKN1A is linked to cancer.