GATA- and its co-factor Friend of GATA (FOG) modulate the basal activity of the HAMP promoter. Huh7 cells were co-transfected with 787·5 ng/well of the full-length wild-type HAMP promoter construct (−1234/+73) along with increasing concentrations (0–787·5 ng/well) of the expression vectors encoding either GATA (1, 3, 4, and 6, A–D) or FOG (1 or 2, E and F) protein. The total DNA concentration transfected was kept at 1·6 μg/well in 12-well plates by adding an empty vector pcDNA3 (Invitrogen). At least three experiments were done in triplicate using three different DNA preparations for each construct. Results are the mean (±S.E.M.) relative change in luciferase activity (fold activation as dark gray bars or suppression as light gray bars) of the HAMP promoter construct with increase in concentrations of either GATA (1, 4, and 6) or FOG (1 and 2) with respect to the cells co-transfected with the promoter construct along with an empty pcDNA3 expression vector (Invitrogen). A different superscript indicates a statistical difference between means (a–rP<0·05).