Background：CD138, a member of the syndecan protein family, is a type I integral membrane heparin sulfate proteoglycan also known as Syndecan-1. Syndecan-1 participates in cell proliferation, cell migration, and cell-matrix adhesion via interaction with collagen, fibronectin, and other soluble molecules （such as FGF-basic）. It is expressed on normal and malignant human plasma cells, pre-B cells, epithelial cells, and endothelial cells.
