SOX2 and breast cancer: MDA-MB-231 cells are ten times more sensitive to this treatment, probably due to the presence of caffeic acid, which is known to act on FOXO1 (Forkhead Box O1), decreasing levels in triple-negative breast cancer [52] FOXO1 increases the probability of forming breast cancer stem cell spheres and simultaneously induces substantial accumulation of SOX2 (sex-determining region Y-box protein 2) [53], which allows cells to differentiate and evolve into other cell types and is responsible for the ability to grow tumor cells [54].