AP-1 binding activity in nuclear extracts from leukemic cells of patients with ATL involves JunD.

(A) Increased AP-1 binding activity in nuclear extracts of leukemic cells of patients with ATL. A, acute-type; C, chronic type. (B) Specificity of the DNA-protein complex formation at the AP-1 site in competition EMSA. Nuclear extracts from leukemic cells of patient 9 were mixed with the labeled IL-8 promoter containing the AP-1 site, in the absence (lane 1) or presence of 100 ng of IL-8 AP-1 site (lane 2), TRE (lane 3), consensus AP-1 (lane 4), or mutated IL-8 AP-1 site (lane 5) competitors. (C) The AP-1 binding complex was recognized by anti-JunD antibody. Nuclear extracts from leukemic cells of patient 9 were preincubated without or with the antisera indicated on top of each lane, before adding the IL-8 AP-1 site probe to the binding mixtures. A supershift band was observed on addition of antisera against JunD (arrow).