Several key questions about this activation mechanism remain unanswered, including how clustering of Sdc1 activates IGF1-R independent of IGF1 ligand, how SSTNIGF1R blocks IGF1 stimulation of IGF-1R in myeloma and whether SSTNIGF1R blocks IGF1-induced IGF-1R activation in tumors other than myeloma. This evidence concerns the gene SDC1 and plasma cell myeloma.