USP8-IN-3 (Compd U51) is a deubiquitinase USP8 inhibitor with an IC50 value of 4.0 μM. USP8-IN-3 also inhibits the proliferation of GH3 and H1957 cells with GI50s of 37.03 μM and 6.01 μM, respectively.In Vitro:USP8-IN-3 (6.25-100 μM; 15 min) inhibits the cleavage activity of USP8 on diubiquitin.