HDAC9 and breast cancer: Novel therapies targeted to HER2/neu, epidermal growth factor receptor (EGFR), vascular endothelialgrowth factor (VEGF), poly(ADP ribose) polymerase (PARP), mammalian target of rapamycin (mTOR), histonedeacetylase (HDAC), the heat shock protein, and cyclin-dependent kinase (CDK) inhibitors have been developed andhave demonstrated some efficacy in breast cancer.