XBP1 and breast cancer: Histone demethylase Kmd5b (aka Jarid1B), which is known for its role in inhibiting differentiation also in neural stem cells (116), Xbp1, a cellular stress response associated transcription factor that has been shown to also enhance hif1a target gene expression in aggressive breast cancer (117), Ssrp1, a part of the Histone chaperone and FACT unit (85), and the histone acetyltransferase Kat7 (aka HBO1), which was recently shown to function as a H3K14 acetylase that is indispensable for re-activation of repressed genes to maintain stem cell plasticity in neural stem cells (118)(Fig. 3E).