CXCL12 and hepatocellular carcinoma: However, it has been shown that this GAG, in the form bound to the plasma membrane heparan sulfate proteoglycan syndecan-4 (SDC4), can bind and enhance the signaling activity of stromal derived factor-1 (SDF-1/CXCL12), resulting in increased growth and invasion of hepatoma cells in response to interaction between this ligand and its receptor, CXCR4 [100].