Transcriptional regulator that acts as an activator. Promotes beta-catenin transcriptional activity. Plays a role in tumorigenesis. Enhances the neoplastic transforming activity of CTNNB1 (By similarity). Found in a complex with CDC73; CTNNB1 and PYGO1. Interacts with CTNNB1. Expressed in breast, ductal and invasive ductal carcinomas of the breast, sporadic colorectal adenomas and carcinomas (at protein level). Expressed in fetal brain. Expressed in lung, amygdala, eye, prostate, pancreatic and prostate cancers, head and neck tumors and embryonal tumor. Tne C-terminal domain is important for its transactivation activity. Belongs to the BCL9 family. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.