DNMT1 and neoplasm: used low-dose chemotherapy drugs to downregulate the expression of DNA-methyltransferase 1 and to stimulate the demethylation of the promoter of the transporter associated with antigen processing 1 gene, thus promoting the expression of human leukocyte antigen G (HLA-G) on the surface of tumor cells, facilitating the killing ability of HLA-G-CAR-NK cells and causing extensive tumor ablation (62).