Marizomib (Salinosporamide A) is a second-generation, irreversible, brain-penetrant, pan-proteasome inhibitor. Marizomib inhibits the CT-L (β5), CT-T-laspase-like (C-L, β1) and trypsin-like (T-L, β2) activities of the 20S proteasome (IC50=3.5, 28, and 430 nM, respectively).