Syndecan-1 also known as SYND1, CD138, SDC1 is a transmembrane (type I) heparan sulfate proteoglycan and is a member of the syndecan proteoglycan family. Syndecan-1 plays a crucial role in cell signaling and adhesion by interacting with components of the extracellular matrix, such as collagens, fibronectin, and thrombospondin. Syndecan-1 is predominantly expressed on pre-B cells, immature B cells, and plasma cells in mice, as well as on the basolateral surfaces of epithelial cells, endothelial cells in sprouting capillaries, and embryonic condensing mesenchymal cells. Expression of Syndecan-1 on these cell types is vital for maintaining tissue architecture and facilitating cellular communication, as Syndecan-1 helps to link the cytoskeleton to the extracellular matrix, thereby influencing cell migration, proliferation, and differentiation.