Matsui, et al. found that both primary tumor cells isolated from MM patients and MM cell lines are composed of a heterogeneous mixture of CD138- and CD138+ populations [4,16], but only the CD138- cells were able to engraft in the bone marrow of NOD/SCID (non-obese diabetic/ severe compromised immunodeficient) mice [18]. This evidence concerns the gene SDC1 and Miyoshi myopathy.