Fig. 3. Hesx1 is a transcriptional repressor with a 36 amino acid repression domain. Increasing concentrations of plasmids expressing the depicted GAL4-Hesx1 fusions were co-transfected with a reporter containing five GAL4 sites upstream of the SV40 promoter (A-C) or E4 promoter (D) driving luciferase into ES cells. Arrows indicate increasing concentrations of transfected GAL4 fusion. In A, B and C, 200 and 500 ng of expression vector were used respectively. In D increasing concentrations of GAL4-Hesx1(1-49) from 50 ng to 500 ng were co-transfected with the E4 promoter fragment (50, 100, 250, 400, 500).