ONX-0914 (PR-957) is a selective inhibitor of low-molecular mass polypeptide-7 (LMP7), the chymotrypsin-like subunit of the immunoproteasome. ONX-0914 blocks cytokine production and attenuates progression of experimental arthritis. ONX-0914 is a noncompetitive irreversible inhibitor of the mycobacterial proteasome (Ki=5.2 μM) . ONX-0914 reactivates latent HIV-1 through p-TEFb activation mediated by HSF-1[1][2][3].