HDAC1 and breast cancer: This finding is consistent with recent findings that G9a knockdown reduces H3K9 methylation and the recruitment of HP1, Dnmt1, and HDAC1 to the promoter of the cell adhesion molecule Ep-CAM and restores its expression in lung cancer cells (31) and that G9a knockdown restores E-cadherin expression by suppressing H3K9 methylation and blocking DNA methylation in human breast cancer cells (32).