Fig. 3. Transactivation of the Epha4 enhancer by the Mesp2/E47 heterodimer. Epha4 somite enhancers (A, 630 bp core sequence; B, six tandem repeats of E-box sequences) were ligated to the pGL3 luciferase vector. Luciferase activity was measured at 36 hours after transfection into NIH3T3 cells. (A) The presence (+) or absence (-) of either Mesp2 or E47 are indicated in each column. (B) Luciferase activity was compared with (black bars) and without (white bars) Mesp2/E47. Mutations in E3 (5'-CATTTG-3'), that give rise to E3m (5'-ACGGGT-3'), results in the loss of reporter activity. The results shown are the mean values from three independent experiments. Standard deviations are indicated by error bars.