Du et al. (2020) showed that mitochondrial sirtuin SIRT4 exerts its tumor suppressive function in BC, while its loss promotes self-renewal of breast cancer stem cells (BCSCs) through the modulation of SIRT1 expression, which regulates the acetylation of histones H4 and cell stemness via BRCA1 [154,215]. Here, BRCA1 is linked to neoplasm.