We also used the embryonic carcinoma cell line P19 to complement our findings with the Bptf knockout ES cells. We co-transfected P19 cells with DNA plasmids carrying four minimal Smad binding elements (SBE), or three activin response elements (ARE), linked to a core promoter and a luciferase reporter gene. The ARE and SBE elements were previously found to be the minimal Smad-responsive elements [53],[54]. Under conditions of Bptf knockdown, we observed a significant reduction in luciferase activity from both reporters (Figure S24A, Figure S24B).
