In order to illustrate the mechanism of AP1 signalling pathway mediated by latent membrane protein 1 (LMP1) encoded by EB virus, the expression of phospho-JNK in Tet-on-LMP1-HNE₂ cell line (L7) was determined at different time by Western blotting, JNK activation increased with the induction of LMP1 in a time dependant manner was abserved. The expression of phospho-JNK and AP1 activity were analyzed by Western blotting and reporter gene in nasopharyngeal carcinoma cell lines which stably expressing LMP1 and the three kinds of its mutants containing different mutation in carboxyterminal activating region. The result showed that no difference existed between HNE₂-LMP1 and HNE₂-LMP1ΔCTAR1, but significant difference between HNE₂-LMP1ΔCTAR2 and HNE₂-LMP1, HNE₂-LMP1ΔCTAR1,2. The phospho-JNK expression and AP1 activity of HNE₂-LMP1 cell lines were individually transfected by dominant negative TRAF(TRAF-DN) and dominant negative TRADD(TRADD-DN). The results showed that the transfection of TRAF-DN or TRADD-DN made JNK expression and AP1 activity decreased significantly. The results suggested that the functional domain CTAR2 of LMP1 encoded by EB virus can mediate JNK signalling pathway through cooperation with TRAF/TRADD complex.