↑ ER-α expression (MDA-MB-231) ↑ sensitivity to E2 and TAM, ↑ PGR mRNA ↑ acH3, H3K9ac, acH4 at the ER-α promoter, especially in combination with TSA ↓ HDAC activity ↓ cell growth ↓ xenograft growth, esp. in comb with TAM ↓ tumor growth, ↓ PCNA staining, ↑ ER-α ↓ DNMT1 and HDAC1 mRNA. This evidence concerns the gene HDAC1 and neoplasm.