Our results are in line with the previously reported worse survival rate of cancer patients with overexpressing class I HDACs, especially HDAC1 and HDAC3 in lung cancers [47], HDAC2 in liver [49] or breast cancers [54], and HDAC1/2/3 in ovarian cancers [55], gastric cancers [56], or sarcomas [57]. Here, HDAC1 is linked to breast cancer.