Msx2-interacting protein (SPEN)

May function as a nuclear matrix system that organizes and integrates transcriptional responses. In osteoblasts, supports transcription activation: synergizes with RUNX2 to boost FGFR2- mediated activation of the osteocalcin FGF-responsive element (OCFRE) (By similarity).

Has also been shown to be an important corepressor protein, which likely regulates different important pathways such as the Notch pathway. Negative regulator of the Notch pathway via its interaction with RBPSUH, which prevents the association between NOTCH1 and RBPSUH, and consequently suppresses the transactivation activity of Notch signaling.