 (A) Luc-reporter assays in P19 cells. Luc-reporters containing SOX3 and SOX9 bound CRMs around the astrocyte specific genes Fgfbp3 and Ttyh1 were strongly activated by SOX9 in synergy with NFIA; an activation that could be efficiently blocked by SOX3. No activation of these reporters could be detected with SOX10 or SOX11. (B) Luc-reporters containing SOX9 and SOX10 bound DNA-regions around the astrocyte genes Aldh1l1 and Atp1a2, which are not expressed in SOX10+ oligodendrocytes, could not be activated by SOX9 or SOX10  