ESR1 and breast cancer: Previous reports indicated that ERalpha and FoxO1 proteins are downstream targets of estradiol.60 Proteomic analysis showed the binding of ERalpha and FoxO1 on estrogen response elements.61 Similarly, FoxO1 colocalizes with ERalpha in the nucleus of breast cancer cells, but estradiol-induced FoxO1 phosphorylation led to nuclear export of the FoxO1-ERalpha complex.62 Although these findings demonstrated coregulation of ERalpha and FoxO1, our results suggest a relationship at the transcription level.