Effect of elevated STAMP on the properties of GR induction of GREtkLUC reporter gene in 293 cells. (A) Dose-response curves for GR induction of GREtkLUC reporter with varying amounts of transiently transfected GR plasmid. S13 (containing stably transfected STAMP) and vector control (VA) cells were cotransfected with GREtkLUC reporter and the indicated amounts of GR-encoding plasmid. Dose-response curves were conducted and plotted as described by Tao et al. . (B) Modulation of Amax, partial agonist activity of the antiglucocorticoid Dex-Mes (%DM), and EC50 by elevated STAMP. Four independent experiments with clone S13 and VA cells such as in A, which included assaying the activity of 1 μM Dex-Mes, were analyzed to yield Amax and EC50 in addition to partial agonist activity of 1 μM Dex-Mes (%DM). The average values ± S.E.M. are plotted. * P < 0.05, ** P < 0.005, *** P < 0.0005 for clone S13 vs. the similarly treated clone VA sample. (C) GR mRNA levels in VA and S13 cells. qRT-PCR was used as described in Materials and Methods to determine the level of GR mRNA in VA and S13 cells with or without 30 ng of transiently transfected GR plasmid (± S.E.M. of triplicates). (D) Western blot with TIF2 antibody of cell lysates from cells transfected with no, or 30 ng of GR plasmid. The lower panel shows the equal levels of the loading control, α-tubulin, in each sample.