ZUP1 and cancer: Beyond the proteasome inhibitors bortezomib (BTZ; also called PS-341) and carfilzomib (CFZ), which are FDA-approved anticancer drugs that target the 20S core, another group of small molecules including b-AP15 and its derivatives that block the deubiquitinase (DUB) activity of the 19S regulatory particle without inhibiting the proteolytic activity of the 20S core particle have been developed and tested in the clinic as potential cancer therapeutic agents1–3.