CTNNB1 and neoplasm: To model a constitutive activation of the canonical Wnt signaling pathway within the OE, as being found in a plethora of human neoplastic diseases, we next bred Sox2-creERT2 mice to Ctnnb1(ex3)Fl/Fl mice and induced the model via single intraperitoneal tamoxifen injection of pregnant females at E14.5.