ESR1 and breast cancer: Lastly, NRF1, a splicing factor was shown to be part of a redox signaling pathway where PTEN and CDC25A were modified by reactive oxygen species, leading to activation of NRF1 and estrogen-induced growth of breast cancer cells [45] and NRF1 was previously included in a Bayesian model of transcription factors involved in estrogen receptor alpha (ER-a).