Fig. 3.

(A) Western blotting of c-Jun, JunD, and Fra-2 expression in CEF either infected with the transformation-deficient virus RCASBP(A) or NY315 RSV or transformed by wt SR-A RSV. Erk-1 was used as a loading control. (B) Identification of the components of AP-1 by EMSA and specific antibodies (Ab) for c-Jun, JunD, Fra-2, and c-Fos. Nuclear extracts were prepared from normal CEF (lanes 1 to 5), SR-A RSV-transformed CEF (lanes 6 to 14), and TPA-treated CEF (lane 15). An asterisk indicates the position of the nucleoprotein complex bound by the antibody. The competitor was a 50 molar excess of the unlabeled TRE oligonucleotide (lane 13) or a mutant form of the TRE (lane 14), added to the binding reaction mixture. (C) Identification of JunD and Fra-2 as factors recruited to the SRU region of the IL-8 promoter by ChIP assays. RCASBP(A)-infected CEF served as controls and were compared to wt SR-A RSV-transformed CEF. An upstream promoter region was studied in parallel and was used as a negative control. IP, immunoprecipitation; pre-imm., preimmune.