Figure 4.

Induction of NF-κB and AP-1 DNA-binding activity in LMP1-transfected cells. Nuclear extracts from C33A cells transfected either with or without LMP1 expression plasmid were mixed with either NF-κB or AP-1 ³²P-labeled probes. Excesses of nonlabeled NF-κB, NF-κB mutant, AP-1 and AP-1 mutant probes (×100) were used as competitors (NF-κB, 5′-GATCGGGTTGCCCCAGTGGAATTCCCCAGCCTT-3; NF-κB mut, 5′-GATCGGGTTGCCCCAGTTTAATTCCCCAGCCTT-3′; AP-1, 5′-GATCTTCTAGACCGGATGAGTCATAGCTG-3′; AP-1 mut, 5′-GATCTTCTAGACCGGATAAGGCATAGCTG). Each of the mutant competitor oligonucleotides has two nucleotide substitutions as indicated by bold letters in binding sequence. Underlined letters indicate binding sequences in the promoter of the MMP9 gene. NS, nonspecific binding.