Using human CAG myeloma cells expressing low versus high levels of HPSE as a test system, it is observed that high HPSE expression promotes an invasive phenotype that depends on VLA-4; VLA-4 is localized to the leading edge when the cells are plated on fibronectin or VCAM-1, and is responsible for cell invasion through filters coated with these VLA-4 ligands (60). This evidence concerns the gene VCAM1 and plasma cell myeloma.