This reviewer report was submitted to the journal in an attached file. Its contents are not displayed directly.

The authors did not answer to a sufficient degree my first and main concern. The source of cc-proteasome (as stated in the paper title) is not clear. Supplementary Figure 2 does not provide conclusive evidence that MVs are the only source of cc-proteasome.

Although explanations were given to some of my concerns, the vast majority of the provided information was NOT included in the manuscript text. This should be done.

The quantification of the 18 and 23 kDa bands in Fig. 7B should be removed from the figure as they are not mentioned in the text, or insert an explanation.