Other mechanisms of PI resistance include overexpression of the proteasome subunit β5, overexpression of other subunits such as β2 and β1, downregulation of 19S proteasomal subunits in MM cell lines and MM patients (55), or overexpression of microenvironmental proteins (IL-6 and IGF-1) and chaperones (59, 60). Here, IL6 is linked to Miyoshi myopathy.