Syndecan-1 is a sponge for growth factors and chemokines,[7] with binding largely via heparan sulfate chains.

[8] The extracellular domain can be cleaved (shed) from the cell surface at a juxtamembrane site,[9] converting the membrane-bound proteoglycan into a paracrine effector molecule with roles in wound repair [10] and invasive growth of cancer cells.

[13] This likely interacts with the cationic face of lacritin's C-terminal amphipathic alpha helix.

[16] This increase results in higher inflammatory responses and tissue damage in experimental models of contact dermatitis,[17] inflammation of the kidney,[18] myocardial infarction,[19] inflammatory bowel disease[20] and experimental autoimmune encephalomyelitis[21] In experimental colitis-induced colon carcinoma, syndecan-1 deficiency promotes tumor growth in an IL-6 / STAT-signaling-dependent manner.

[23][24] In breast cancer, syndecan-1 is up regulated and contributes to the cancer stem cell phenotype, which is linked to increased resistance to chemotherapy and radiation therapy [25][26][27] It is a specific antigen on multiple myeloma cells.