SDC1 and plasma cell myeloma: To extend these findings, we find that P3-X63-Ag8 myeloma cells also (i) display Sdc1-coupled VEGFR2 and VLA-4 (Supplementary Figure S6), (ii) activate VEGFR2 when attached to FN, which is blocked by the SSTN peptides (Figure 6e), (iii) bind and spread on FN, but fail to attach in the presence of SSTN210-233 or to spread in the presence of SSTN214-240 (Supplementary Figure S6) and (iv) fail to migrate through FN-coated filters in the presence of these peptides, or in the presence of VLA-4, VEGFR2 or HPSE inhibitors (Supplementary Figure S6).