HDAC3 and breast cancer: There were two possible explanations for the above results: (i) HDAC3 protein transferred from the nucleus to the cytoplasm during breast cancer cell establishment in the brain, which indicated that the biological function of HDAC3 in cells of this subtype might have changed; (ii) a subset of breast cancer cells with high cytoplasmic expression of HDAC3 in primary tumors had a higher metastatic potential, and therefore, such cells were enriched in the brain metastases.