Analysis of DNA-protein interactions within the EBNA2RE 5′ domain of the LMP2A promoter. An EMSA is shown with nuclear extracts of BL41-P3HR1 cells and of BL41-P3HR1 cells stably transfected with either EBNA2 or mNotch1-IC, which were incubated with the 32P-labelled 54-bp oligonucleotide O54 consisting of positions −209 to −262 relative to the LMP2A RNA start site. To show that EBNA2 or mNotch1-IC is a component of the complex IVE/IVN, the monoclonal anti-EBNA2 antibody R3 or the anti-FLAG monoclonal antibody M2 was added, respectively. Complexes were separated on a 4% polyacrylamide gel. The positions of complexes I, III, IVE, IVN, IVE*, and IVN* are indicated.