The protein encoded by this gene binds CTNNB1 and prevents interaction between CTNNB1 and TCF family members. The encoded protein is a negative regulator of the Wnt signaling pathway. Two transcript variants encoding the same protein have been found for this gene. ICAT interacts directly with β-catenin and interferes with the Wnt signaling pathway. Specifically, ICAT prevents the interaction of β-catenin with TCF-4 and inhibits β-catenin--TCF-4-mediated transactivation. The negative regulatory effect of ICAT on the Wnt signaling pathway appears to inhibit tumor cell proliferation. ICAT also induces G2 arrest followed by cell death in colorectal tumor cells. The ectopic induction of ICAT inhibits the expression of β3 Tubulin and thus neuronal differentiation in embryonal carcinoma P19 cells. Structural characteristics of ICAT include a three-helix bundle and a C-terminal tail. The gene encoding human ICAT maps to chromosome 1p36.22.