CDH1 and breast cancer: To address this issue, we analyzed the methylation status of CDH1 gene coding E-cadherin based on previous reports, and found that the CDH1 promoter region was mostly in a hypomethylation status in tumor specimens from breast cancer patients and MCF7 cells (Terada et al., 2009; Huang et al., 2019), suggesting that E-cadherin expression is not simply regulated by the methylation status of CDH1. It is thus crucial to consider the possibility that other pivotal genes might also be regulated after treatment of tumor cells with 5-Aza-CdR, besides the expression of SIPA1 and E-cadherin.