CDKN1A and malignant colon neoplasm: A concentration–response study of Vit-C in culture medium with the human colon cancer HCT116 cell line showed re-expression of p21 (CDKN1A) at 50 μM, increased abundance of 5hmC at concentrations up to 100 μM with no effects on 5mC by LC/MS-MS, and cytotoxicity above 1 mM [644].