Dose-response relationships for compounds not anticipated to affect globin gene expression (proline, cysteine, arginine).

For each compound, experiments were performed in triplicate at each concentration shown, and mean values are plotted. Concentrations of cysteine and arginine greater than 10 mmol/L and 20 mmol/L, respectively, were toxic to the cells. ▪ indicates mean values for propionic acid (from Figure 2). Notice that none of the tested compounds increased γ-firefly luciferase activity.