FOXO3 and breast cancer: Both EGCG and retinoids have been demonstrated to activate Foxo3a: in Trastuzumab-resistant HER2-driven breast cancer cells [49] and in ERα-positive breast cancer cells [50] the activation of Foxo3a by EGCG played an important role in the resulting cytotoxicity: all samples treated with EGCG + IIF and IIF alone for 24 h showed a significant increase in Foxo3a RNA expression.