HDAC9 and breast neoplasm: By comparing HDAC expression at the mRNA level in a panel of human breast tumor cell lines classified as luminal, basal A and basal B [13, 14], we found the level of HDAC9 expression to be strikingly increased in basal cells (mean ± SD = 223.7 ± 197) as compared to luminal cells (mean ± SD = 14.2 ± 10.7) (p = 0.0059) (Figure 1A).