PRKDC and Miyoshi myopathy: Since protease digestion of DNA-PK and Ku proteins are enhanced by proteasome inhibition (i.e. bortezomib treatment) in MM cell lines [32] these data taken in aggregate further suggest that proteolytic enzymes that are capable of digesting Ku proteins are constitutively activated, and possibly accumulate and/or become further activated under proteasome inhibition in MM cells.