Figure 4.

Minimum enhancer cis element defined by deletion analysis. A 5′-end-labeled synthetic 9-mer (cis9; lane 3) or oligonucleotides (lanes 4–7) with deletions from either their 5′ or 3′ end (indicated at the bottom of the figure) were incubated with CEM nuclear extract before the band-shift assay. Only the 16-bp (lane 2) and cis9 (lane 3) fragment that contains the full 9-bp sequence show protein binding (arrows), suggesting that this 9-bp fragment is the minimal enhancer element. Lane 1 shows the 16-bp sequence without nuclear extract.