Consistent with the IHC data, western blot analysis of protein extracts from 22 samples of CD138+ MM cells demonstrated a prominent shift toward increased XBP-1s expression in the majority of MM primary tumor samples relative to normal plasma cells (Figures 1B and 1C), a pattern also evident in MM cell lines (Figures 1C–1E). Here, SDC1 is linked to Miyoshi myopathy.