HDAC9 and breast cancer: A California cancer consortium study revealed that SAHA alone failed to achieve success in the treatment of 14 patients with metastatic breast cancer.32 In our study, we observed that the pan-HDAC inhibitors SAHA and LBH589 promote breast cancer invasion and metastasis in vitro and in vivo, which in turn will impede the efficacy of HDAC inhibitors in breast cancer.