HDAC9 and breast cancer: It is worth mentioning that in the human breast cancer cell line MCF-7, the chromatin decondensation that is promoted in response to VPA-induced HDAC inhibition is accompanied by an increased sensitivity of DNA to nucleases and an increased association of DNA with intercalating agents that have been assumed to be modulated by the depletion of non-histone proteins involved in the maintenance of chromatin structure (SMC) [7].