Recent advances in drug discoveries and understanding of epigenetic regulation of gene expression have brought histone deacetylases (HDACs) in spotlight. Breast Cancer Metastasis Suppressor 1 (BRMS1), a gene shown to functionally suppress metastasis of breast cancer and melanoma, is a member of mSin3-HDAC complex. This chapter reviews the emerging understanding of the molecular mechanisms of BRMS1 action and possible players involved in it. New evidence of BRMS1-family of proteins and their possible role in histone code is discussed.