In a separate cohort, we observed that the Heca452-positive CD38/CD138 plasma cells were significantly enriched in the CD45-positive fraction, which may indicate a more immature phenotype (Supplementary Figure 8).34 Taken together, these data indicate that a proportion of primary MM cells express E-selectin ligands and have the potential to bind E-selectin, and these cells are more abundant in RRMM patients. Here, SDC1 is linked to Miyoshi myopathy.