Transcriptional regulator that acts as an activator. Promotes beta-catenin transcriptional activity. Plays a role in tumorigenesis. Enhances the neoplastic transforming activity of CTNNB1. Found in a complex with CDC73; CTNNB1 and PYGO1 (By similarity). Interacts with CTNNB1. localized also in punctate nuclear bodies as well in the cytoplasm. Colocalizes with CTNNB1. Expressed in kidney, liver, lung, testis, brain, spleen, heart and skeletal muscle. Highly expressed in numerous colorectal tumors compared to corresponding non-cancerous tissues. Expressed in embryo. Tne C-terminal domain is important for its transactivation activity. Belongs to the BCL9 family.