Fig. 1: Pathogenesis of extramedullary spread in multiple myeloma.

SDF-1- Stromal cell derived factor-1, CXCR-4- Chemokine receptor type 4, VLA-4- Very late antigen-4, VCAM-1- Vascular cell adhesion protein-1, VEGF- Vascular endothelial growth factor, TNF-a- Tumor necrosis factor- alpha, HGF- Hepatocyte growth factor, IL-6- Interleukin-6.