DNMT1 and breast cancer: Previous studies in our laboratory observed that 6-TG blocked DNMT1 activity markedly, leading to inhibition of MDA-MB-231 cell growth and induction of apoptosis through reactivating methylation-silenced genes in the apoptosis pathway and PI3K–AKT signaling pathways, and also inducing FAS-mediated exogenous apoptosis and p21-dependent G2/M arrest in MCF-7 breast cancer cells (Li H. et al., 2020; Zhang et al., 2020; Chu et al., 2022).