CTNNBIP1 (catenin beta interacting protein 1) is a negative regulator of Wnt/β-catenin signaling that functions primarily through preventing the interaction between β-catenin (CTNNB1) and TCF transcription factors 1. The protein acts as a repressor of β-catenin-mediated transcriptional activation, thereby suppressing expression of β-catenin target genes including MMP7, EGFR, and CCND1 12. CTNNBIP1 expression is spatially regulated in the liver, with periportal zonation opposing pericentral Wnt receptor expression 3. The gene is epigenetically regulated; promoter hypermethylation suppresses CTNNBIP1 expression in lung and breast cancers 12. Additionally, alternative polyadenylation of CTNNBIP1 through PABPN1 phase separation disruption promotes colorectal cancer proliferation 4. Clinically, CTNNBIP1 acts as a tumor suppressor. Low expression correlates with enhanced cancer migration in lung cancer and poor prognosis in triple-negative breast cancer 12. Beyond cancer, CTNNBIP1 upregulation suppresses Wnt pathway activation in psoriasis 5, and a CTNNBIP1-CLSTN1 fusion RNA regulates retinal progenitor cell fate during human retinal development 6. MicroRNA-215 post-transcriptionally suppresses CTNNBIP1 during adipogenesis 7.