ESR1 and breast neoplasm: FOXO3 was reported to positively regulate ESR1 expression, the expression of a dominant negative form repressing expression of ESR1 in MCF-7 cells [187], and binding sites were identified in promoters A and B. However, FOXO3 was also reported to suppress the transcriptional activation properties of ERα via protein–protein interactions and to suppress growth of ER+ breast tumor cells [188].