The 293T cells were transfected with the indicated plasmids using Lipofectamine 2000 Reagent (Thermo Fisher Scientific). After 48 h, cells were collected, and immunoprecipitation and Western blot assay were performed as previously described (50 (link)). For the endogenous interaction between YAP and p65, ATL cell lysate was incubated with anti-YAP antibody (Cell Signaling Technology) or anti-mouse immunoglobulin G (IgG) (Santa Cruz Biotechnology), and the following procedures were the same as described above in 293T cells. Other antibodies used were as follows: anti-FLAG M2, anti-HA, anti–c-Myc (Sigma-Aldrich), anti-p65, anti–phospho-YAP (Ser127), anti–phospho-YAP (Ser381), anti-GAPDH (Cell Signaling Technology), and anti-Tax was used as previously described (51 (link)).