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. Has also been shown to play a role in regulating the intracellular trafficking of polycystin-2/PKD2 and possibly of other intracellular proteins. Promotes adipocyte and cardiomyocyte differentiation. Homodimer. Interacts with polycystin-2/PKD2 and GM130. Interacts with the C-terminal region of CTNNB1. Interacts (C-terminus) with TCIM (C-terminus), TCIM competes with CTNNB1 for the interaction with CBY1. Interacts with FAM92A; this interaction facilitates targeting of FAM92A to cilium basal body. Interacts with CIBAR2. Found in heart, brain, lung, liver, muscle, kidney and testis. Levels are approximately 3-fold higher in embryonic and adult heart than in lung or liver. Ubiquitously expressed in early stages of embryonic stem cell differentiation but decreases at later stages when high expression is restricted to cardiomyocytes. 'Chibby' is Japanese for 'small'; the gene was so named for the RNAi phenotype seen in flies. Belongs to the chibby family.