POU5F1 and cancer: Contrary to the previous study that CRB3 knockout mice displayed high levels of cytoplasmic β‐catenin in the intestine, which indicates a low activity of the Wnt signalling pathway,30 we found that CRB3 overexpression inhibited the Wnt signalling pathway, which led to decreased expression of downstream genes (CD44 and cMyc) and cancer stem cell factors (OCT4 and NANOG), and that these genes were up‐regulated when cells acquired tamoxifen resistance.