Effect of stably transfected STAMP on the growth rate of 293 cells. (A) Increased STAMP decreases cell growth. The number of cells in replicate plates of clone S13 (S) and VA (V) cells (no steroid, cells removed from G418 1 day prior) after increasing days was assessed by the CellTiter One Solution assay. The average value (± S.E.M.) of four independent experiments is shown. **P < 0.005, ***P < 0.0005. (B&C) FACS analysis of VA and S13 cells (no steroid, cells removed from G418 upon seeding; S = single cells, D = double cells). The number of dead cells after increasing days in one of three representative experiments is plotted in C (± SD, n = 3, *P < 0.05, **P < 0.005). (D) Growth of VA and S13 cells after removal from G418 for more than 1 month. Experiment was conducted and plotted (± S.E.M., n = 4, *P < 0.05) as in A except that 1 μM Dex was added to cells as indicated. (E) Increased STAMP decreases cell growth ± steroid. Experiment was conducted as in D except that four different steroids (100 nM aldosterone, 1 μM Dex, 20 nM R5020, and 10 nM R1881) were added. Similar results were obtained in two additional independent experiments. In some cases (e.g., S13 cells in Fig. 1A), the error bar length is smaller than the symbol.