Acts as a transcriptional coregulator, that can have both coactivator and corepressor functions. Inhibits the DCSTAMP-repressive activity of TAL1, hence enhancing the access of the transcription factor MITF to the DC-STAMP promoter in osteoclast. Plays a role in bone homeostasis; required as a positive regulator in TNFSF11//RANKL- mediated osteoclast fusion via a DCSTAMP-dependent pathway. May also be required in the regulation of osteoblast differentiation (By similarity). Involved in the transcriptional corepression of NF-kappaB in macrophages (PubMed:18025162). Plays a role as a regulator in the pro-inflammatory cascade (PubMed:18025162). . This is the function of SBNO2 (strawberry notch homolog 2, ENSG00000064932).