Gel mobility shift assay using wild-type and mutant oligonucleotide sequences. A radiolabeled wild-type oligonucleotide encompassing the HNF-4 binding site (−76 to −47) in the factor VII gene shows specific binding to a protein present in human liver nuclear extracts (lane 1). Reactions performed with incubation of unlabeled competitor oligonucleotides at 10× and 500× concentrations of wild-type (lanes 2 and 3, respectively) and the mutant sequence (lanes 4 and 5, respectively) are shown. Lanes 6 through 10 show the absence of binding using a 30 bp radiolabeled oligonucleotide containing the T to G mutation at position −61 in the absence of cold competitor (lane 6), and in the presence of 10× and 500× concentration of cold competitor with either the wild-type sequence (lanes 7 and 8) or the mutant sequence (lanes 9 and 10). The nucleotide sequences of the wild-type and mutant probes are shown below.