HDAC9 and breast cancer: To identify whether the down-regulation of HDAC4 impacted on other class II HDACs in human breast cancer, RNA expression of HDAC5, HDAC7, and HDAC9 were examined in cells overexpressing miR-125a-5p or depleted for HDAC4. The results show that the expression of HDAC4 and HDAC5 was also decreased by overexpression of miR-125a-5p, while HDAC7 and HDAC9 were not affected.