Interestingly, a recent study by Bennesch et al. demonstrated that recruitment of the CoREST complex is essential for LSD1 function in the activation of the ER pathway in breast cancer cells, thus indicating that repressive complexes may perform gene activation functions in specific cell types, although further studies are needed to fully elucidate the molecular intersection of the ER pathway and CoREST complex activity (44). Here, RCOR1 is linked to breast cancer.