In this study, GRP78 protein expression and levels in plasma of bone marrow blood samples were studied in patients with different stages of myeloma disease (MGUS, NDMM, RRMM) to evaluate GRP78 as a marker to discriminate plasma cell disorders, i.e. stratifying for patients having MM cell clones with high resistance to ER-stress and proteasome inhibition. Here, HSPA5 is linked to Miyoshi myopathy.