For instance, SIRT1 alters the acetylation patterns of histones H3 and H4, including H3k4ac, H3k9ac and H4k16ac, to regulate the expression of cancer-related genes in breast cancer.390 Besides the impact on chromatin state, SIRT1 modulates the non-histone proteins to initiate DNA repair and gene transcription. Here, SIRT1 is linked to breast cancer.