PSMB5 and Miyoshi myopathy: In addition to the PSMB5 mutations, resistant MM cell lines have frequently been found to overexpress the β5, β2, and β1 subunits of the proteasome, usually accompanied by increased catalytic chymotrypsin, trypsin, and caspase-like activity, respectively, and subsequent higher cellular survival rates as compared to sensitive cell lines [37,38,39].