Fig. (2) Binding to NFI Sites of the HPV16 URR. (A) Double stranded oligonuclotides representing the 7 NFI half sites of the HPV16 URR were labeled as probes and used in electrophoretic mobility shift assays (EMSAs). The nucleotide sequence for each probe is shown. (B) Nuclear extract (12 µg of protein) from HKc/HPV16 was incubated with each probe. Protein-probe complexes were separated from the free probe on a 5% non-denaturing polyacrylamide gel. Specific NFI binding as well as non-specific (NS) binding is noted. Addition of cold competitor (125X) illustrates specific NFI binding (lane 9).