Cell-permeable. Abrogates the deubiquitinating activity of the 19S regulatory particle by inhibiting ubiquitin C-terminal hydrolase 5 (UCHL5) and ubiquitin-specific peptidase 14 (USP14) resulting in accumulation of polyubiquitin in cells. NSC-687852 induces tumor cell apoptosis and tumor progression in four different solid tumor models in vivo.