Tax induces AP-1 binding activity, involving JunD.

(A) Nuclear extracts isolated from JPX-9 cells, treated with CdCl₂ (20 μmol/L) for the indicated time periods, were subjected to EMSA. (B) Northern blot analysis for expression of Tax mRNA in JPX-9 cells treated with CdCl₂. (C) Western blot analysis for expression of Tax protein in JPX-9 cells treated with CdCl₂. (D) Nuclear extracts from JPX-9 cells treated with CdCl₂ for 48 hours were mixed with the labeled IL-8 AP-1 probe in the absence or presence of 100 ng of the cold competitor, indicated on top of each lane. (E) JPX-9 nuclear extracts obtained after 48 hours of CdCl₂ treatment were incubated with the indicated antibodies, before addition of the labeled IL-8 AP-1 probe, and analyzed by EMSA. A supershift band was observed on addition of antisera against JunD (arrow).