LANA induces DNA binding of a Jun-Fos heterodimer to the AP1 RE but does not directly bind to the AP1 RE. (A) AP1 EMSA using nuclear extracts from 293-TetOff-EGFP-LANA cells treated without (lanes 1-10) or with (lane 11) dox (1 μg/mL). Cold competition with excess wild-type AP1 probe abrogated the gel-shifted band (lane 2), whereas cold mutant probe had no effect (lane 3). Supershift experiments are shown in lanes 4 to 10. (B) EMSAs on nuclear extracts from BCBL-1 cells. Experiments were similar to those in panel A, including cold competition and supershift experiments.