Likewise, conditional deletion of Notch1 in mouse skin epidermis60 or activation of β-catenin in hair follicles stem cells by deleting Ctnnb1 exon 361 leads to over-activation of the WNT/β-catenin pathway and induction of tumours/growths in a non-cell autonomous manner. The gene discussed is CTNNB1; the disease is neoplasm.