CTBP1 and osteosarcoma: Furthermore, studies in human osteosarcoma cells demonstrate that transcription factors and complexes modulate GAS5 expression; the C-terminal binding protein 1 (CtBP1)-histone deacetylase 1/2 (HDAC1/2)-Interferon regulatory factor 1 (IRF1) complex, for example, can interact with the GAS5 promoter to repress its expression [43].