CTNNB1 and colorectal carcinoma: HCT116 cells, isolated from colorectal carcinoma, are heterozygous for an activating mutation in CTNNB1 (ΔS45) that prevents it from being phosphorylated by casein kinase 1 alpha (CSNK1A1), which normally marks the protein for further phosphorylation and proteasomal degradation4.