MTOR and breast cancer: Additional studies on the effects of quercetin on cancer stem cells (CSCs) have shown that this flavonoid represses cell viability and clone formation of CD44-/CD24- BC cells, while reducing metastasis formation in nude mice, which were effects mediated by decreased levels of cyclinD1 and Bcl-2 and by the downregulation of the phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR pathway [113].