Bortezomib dramatically improves TPO^high mice survival. Kaplan-Meier plots of untreated (vehicle) or treated (bortezomib 0.5 mg/kg and 0.25 mg/kg) TPO^high mice. Bortezomib (0.5 mg/kg) significantly improves survival (P ≤ .001). Pooled data from 9 to 13 animals per experimental group studied from 16 (after 12 weeks of treatment) to 52 weeks after engraftment. Bzb indicates bortezomib.