Depletion of NIK in ATL cells suppresses tumor formation in NOD-SCID/γc^null (NOG) mice. (A) Pools of ED40515(−) cells expressing Ctli or NIKi-1 and -2, shown in Figure 6B, C, D, and E, were analyzed for cell growth in vitro by the trypan blue staining method. Relative cell numbers, in comparison with control cells (arbitrarily set at 1), are shown. Data are expressed as mean plus or minus SD of 3 independent experiments. P values are vs control (Ctli + Ctli). n.s. indicates no significant difference. (B-D) NOG mice were inoculated subcutaneously in the postauricular region with the puromycin-resistant ED-40515(−) cells (5 × 10⁶). Tumor formation in mice was evaluated 2 weeks after inoculation. Tumor weight (B) and size (C) relative to those of tumors formed in mice inoculated with ED40515(−) cells expressing Ctli are shown. (D) Photographs of tumors formed 2 weeks after cell inoculation. Each result was obtained from 5 different mice (means are shown [error bars]). P values are versus control (Ctli + Ctli).