CTNNB1 and colorectal cancer: CTNNB1 and TCF7L2 are essential only in colorectal cancer cell lines, where activation of the Wnt pathway results in accumulation of B-catenin that interacts with and acts as a coactivator for TCF7L2 that in turn activates downstream genes responsible for colorectal cancer cell survival as well as resistance to chemo-radiotherapy (36–38).