Figure 4. Stat3 cooperates with NF-κB in the context of HTLV-1 -transformed T cells.

(A) MT-2 or (B) SLB-1 cells were treated with DMSO, U0126, LY294002 or BAY11-7805 (5μM) for 4 hours. The activities of NF-κB, Stat3 and AP-1 were evaluated with EMSA. EMSA was employed to determine the activities of NF-κB, Stat3 and AP-1 in NS- or IKKγ-depleted MT-2 (C) and SLB-1 (D) cells. (E) Tax was co-transfected with vector, IKKβ_KM (the dominant-negative mutant of IKKβ) or IκBβ in HEK293 cells. The nuclear extracts were examined for the activities of NF-κB and Stat3 with EMSA. The NF-κB and Stat3 activities were shown in the upper panel. The total lysates were analyzed with Western Blot (WB) (lower panel). (F) Parental HEK293 cells were stimulated with TNFα (20ng/ml) or the conditioned culture media from the HEK293 cells transfected with Tax, M22 or IKKβ_KA (the constitutively active form of IKKβ) for 4 hours. The activities of NF-κB and Stat3 were analyzed by EMSA (upper panel). Proteins expression was shown in the lower panel. (G) Jurkat T cells were stimulated with the conditioned culture media from SLB-1 or MT-2 or with TNFα (20ng/ml) for 4 hours. The activities of NF-κB and Stat3 were analyzed by EMSA. Sup: supernatant; Ctl: the fresh complete medium for control.