“…Previously, the expression of many important DNA repair genes (e.g., CRY1 , ERCC1 , LIG4 , MLH1 , MSH2 , MSH6 , MSH7 , OGG1 , PCNA , RAD21 , RAD50 , XRCC1 , and XRCC4 ) in human, animal, or plant cells were found to be suppressed by Cd [6,8,13,29,30]. In Zhou et al, the overexpression of DNA methyltransferase genes ( DNMT1 and DNMT3a ) resulted in the silencing of DNA repair genes ( MSH2 , ERCC1 , XRCC1 , and OGG1 ) in CdCl 2 -transformed human bronchial epithelial 16HBE cells and tumorigenic cells isolated from a xenograft nude mouse model [7].…”