Thus, like several other soluble factors expressed by MM cells, for example vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) [53]–[55], DKK1 can both, exercise paracrine effects on the BM microenvironment, and affect the MM cells in an autocrine fashion the net effect could be either enhanced or reduced tumor growth. Here, HGF is linked to neoplasm.