Although the b.i.-NOD/SCID+CD122-Ab approach also revealed substantial BM-engraftment (Figure 1A+B), the NSG i.t. approach showed metastatic disease spread, since MM cells engrafted the i.t.-injection and disseminated to additional BM sites, thereby recapitulating the systemic nature of the disease (Figure 2A). This evidence concerns the gene IL2RB and metastatic neoplasm.