PR-619 is a broad-spectrum and reversible inhibitor of the deubiquitinylating enzymes (DUBs) with EC50 of 1-20 μM and it was developed for chemotherapy.

P005091 acts as a selective inhibitor of ubiquitin-specific protease 7 (USP7) and USP47 with the EC50s of 4.2 μM and 4.3 μM respectively.

IU1 is a cell-permeable, reversible and selective proteasome inhibitor of human USP14 with IC50 of 4.7 μ M, 25-fold selective to IsoT.

P22077 is an inhibitor of ubiquitin specific protease USP7 (EC50 = 8.6 μM). P22077 also inhibits the deubiquitinase USP47.

NSC 632839 HCl is an nonselective inhibitor of isopeptidase and inhibits various proteins including USP2, USP7, and SENP2 (EC50 = 45 ± 4 μM, 37 ± 1 μM, and 9.8 ± 1.8 μM, respectively).