SIRT1 and breast cancer: Although SIRT1 is known to be regulated by several transcription factors, microRNAs, endogenous regulators such as AROS (active regulator of SIRT1) and DBC1 (deleted in breast cancer 1)18, 19, 20, 21, and post-translational modifications, including SUMOylation22 and deubiquitylation23, the molecular machinery to regulate the expression and the activity of SIRT1 are quite complex and still remains under investigation.