FOXO3 and breast cancer: Despite the dysregulation of FoxOs factors has emerged as a key molecular feature of endocrine resistance mechanisms [9,24,52,53], very few clinical trials investigating the efficacy of PI3K or AKT inhibitors in BC tumors, included the evaluation of FoxO3a expression and/or subcellular localization as a secondary outcome (https://clinicaltrials.gov/, Identifiers: NCT02077569 [54], NCT02260661, NCT01339442, accessed on 10 September 2021).