Transcriptional repressor that may play a role in the specification and differentiation of lung epithelium. May also play a role in developing neural; gastrointestinal and cardiovascular tissues. Can act with CTBP1 to synergistically repress transcription but CTPBP1 is not essential. Plays a role in synapse formation by regulating SRPX2 levels. Involved in neural mechanisms mediating the development of speech and language.