An inhibitor of deubiquitinating enzymes inhibits UCH-L1 UCH-L3 and USP8 in a cell-free assay at 10 UM as well as USP5 in a reporter assay at the same concentration inhibits the 26S proteasome but not the 20S proteasome in a reporter assay using HeLa cancer cells at 10 UM increases the levels of polyubiquitinated proteins in HeLa and TOV21G1 cancer cells at 5 UM induces cell cycle arrest at the S and G2/M phases in HeLa cells at 10 UM decreases the viability of nine cancer cell lines (IC50s 1.64-12.49 UM) increases survival and decreases tumor and ascitic fluid mass in an ES-2 ovarian cancer mouse xenograft model at 5 mg/kg every other day