The study demonstrated that DNMT1 deletion in colorectal cancer cells led to an upregulation of TET2 expression, re-expression of tumour suppressor proteins (p16ink4A and p15ink4B), CDKN2A promoter demethylation, and associated resistance to DNMTi in DNMT1-deleted cells [81]. The gene discussed is CDKN2A; the disease is colorectal cancer.