(A) Plasma cells were visualized by stereo microscope after Giemsa staining of bone marrow aspirates. Asterisks mark plasma cells. (B) Immunohistochemistry (IHC) with GRP78 antibody was performed in formalin-fixed bone marrow smears in patients with MGUS, NDMM and RRMM. No significant differences in GRP78 staining intensity and localization of GRP78 could be observed between plasma cells in MGUS, NDMM and RRMM patients. (C) Statistical analysis of GRP78 expression in patients with MGUS, NDMM and RRMM after IHC on air-dried, formalin-fixed bone marrow smears. Mean staining intensity/plasma cell. No significant differences in GRP78 staining intensity and localization of GRP78 could be observed between plasma cells in MGUS, NDMM and RRMM patients (p = 0.12).