Though it has been reported that loss of function of BRCA1 in breast cancers or cell lines enhances the expression of several EMT inducing transcription factors including SLUG 5, TWIST 20, FOXC1/C2 21, and reduces the expression of a few EMT suppressing transcription factors, such as FOXA1 22, 23, FOXO3 24, 25, none of these transcription factors has been identified as downstream mediators of BRCA1 in the regulation of EMT in mammary tumor development and progression. Here, FOXO3 is linked to breast cancer.