Abstract: Methods for modulating proteasome activity in a subject is provided. Proteasome activity is modulated by administering a therapeutically effective amount of proteasome modulating pharmacological agent to a subject. In a preferred embodiment, the proteasome modulating pharmacological agent is a protease inhibitor. In another aspect, a screening assay for detecting and identifying proteasome modulating pharmacological agents to modulate proteasome activity in a subject is also provided.