PSMD14 and cancer: POH1 knockdown could dramatically inhibit GFPu protein degradation in HEK-293 cells and induce ubiquitinated protein accumulation in HepG2 cancer cells, and this disassembly of 26S proteasome could mostly blocked the effects of CuPT on protein degradation and ubiquitinated protein accumulation, indicating that CuPT-mediated proteasome malfunction did rely on the existence of intact 26S proteasome.