To determine if the enhancer activity acts specifically on the ADH4 promoter, we tested it in combination with two heterologous promoters. 4E increased the activity of another ADH promoter, the ADH1B basal promoter (1Basal), by 180-fold (p = 2 × 10−12) in HepG2 cells. It increased the activity of SV40 promoter (SV40Basal) by 56-fold (p = 8 × 10−10).