To localize functional elements within the 1504 bp region, this region was subdivided into three fragments, 4E1, 4E2 and 4E3 (Figure 1C). The enhancer effect of 4E was contained within the 4E3 fragment, which enhanced the activity of 4Basal by 46-fold (p=5 × 10−15) (Figure 3). 4E1 repressed the activity of 4Basal by 50% (p < 0.001), whereas 4E2 increased the activity by 1.2-fold (p = 0.05). As the activity of 4E3 was not different from the parent fragment 4E (p =0.13), we focused on the 4E3 fragment for further characterization.
