Abstract: The invention relates to methods of treating protein degradation disorders, such cellular proliferative disorders (e.g., cancer) and protein deposition disorders (e.g., neurodegenerative disorders). The invention provides methods and pharmaceutical compositions for treating these diseases using aggresome inhibitors or combinations of aggresome inhibitors and proteasome inhibitors. The invention further relates to methods and pharmaceutical compositions for treating multiple myeloma. New HDAC/TDAC inhibitors and aggresome inhibitors are also provided as well as synthetic methodologies for preparing these compounds.