CTNNB1 and thyroid gland undifferentiated (anaplastic) carcinoma: Activation of the Wnt/β-catenin signaling is often caused by activating mutations of CTNNB1 (which encodes β-catenin) in thyroid cancer, particularly in poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid carcinoma (ATC) [42, 43].