The protein encoded by this gene is a member of the Mastermind-like family of proteins. All family members are proline and glutamine-rich, and contain a conserved basic domain that binds the ankyrin repeat domain of the intracellular domain of the Notch receptors (ICN1-4) in their N-terminus, and a transcriptional activation domain in their C-terminus. This protein binds to an extended groove that is formed by the interaction of CBF1, Suppressor of Hairless, LAG-1 (CSL) with ICN, and positively regulates Notch signaling. High levels of expression of this gene have been observed in several B cell-derived lymphomas. Translocations resulting in fusion proteins with both CRTC1 and CRTC3 have been implicated in the development of mucoepidermoid carcinomas, while a translocation event with CXCR4 has been linked with chronic lymphocytic leukemia (CLL). Copy number variation in the polyglutamine tract has been observed. [provided by RefSeq, Jan 2015].