ONX-0914 (PR-957) TFA is a selective, noncompetitive, irreversible inhibitor of the chymotrypsin-like subunit (LMP7) of the immunoproteasome, effectively blocking cytokine production and mitigating experimental arthritis progression. With a K_i value of 5.2 µM against the mycobacterial proteasome, ONX-0914 TFA also reactivates latent HIV-1 by inducing p-TEFb activation through HSF-1 mediation [1] [2] [3].