Inhibits the Wnt/Wingless pathway by binding to CTNNB1/beta- catenin and inhibiting beta-catenin-mediated transcriptional activation through competition with TCF/LEF transcription factors (PubMed:12712206, PubMed:19435523). Has also been shown to play a role in regulating the intracellular trafficking of polycystin-2/PKD2 and possibly of other intracellular proteins (PubMed:15194699). Promotes adipocyte and cardiomyocyte differentiation (By similarity). {ECO:0000250|UniProtKB:Q9D1C2, ECO:0000269|PubMed:12712206, ECO:0000269|PubMed:15194699, ECO:0000269|PubMed:19435523}. This is the function of ENSG00000100211 (CBY1, chibby 1, beta catenin antagonist).