(A) Luciferase activity under the control of normal, deleted, or mutated 4 promoter in IC-2 cells. (B) The effect of overexpression of +- or mi-MITF on the luciferase activity in IC-2 cells. The luciferase gene under the control of the normal, deleted, or mutated 4 promoter was cotransfected with +- ormi-MITF or with the expression vector. The data represent the mean ± SE of five experiments. In some cases, the standard error was too small to be shown by bars.