Inhibition of tumor growth in mice given transplants of Tax tumor. (A) Five Rag-1 immunodeficient mice at 8 weeks of age in each group were injected with SC cells subcutaneously and 2 days later were treated with PS-341 similarly for 8 weeks as described in Figure 5. The tumor volumes for all animals in each group at weeks 2, 4, 6, and 8 are plotted with SE measurements. The statistical significance of the response to PS-341 treatment on tumor growth was evaluated by a paired t test: P ≤ .01 for vehicle treated compared to PS-341 treated groups. (B) Survival curves of animals under PS-341 or saline treatments were monitored and statistical significance determined using a paired t test: P ≤ .05 for vehicle-treated compared to PS-341–treated groups.