SIN3B acts as a transcriptional repressor. It interacts with MXI1 to repress MYC responsive genes and antagonize MYC oncogenic activities. Also, it interacts with MAD-MAX heterodimers by binding to MAD. The heterodimer then represses transcription by tethering SIN3B to DNA. The gene is also able to form a complex with FOXK1 which represses transcription