SDC1 and glioblastoma: Because syndecans become expressed in the reactive astrocytes surrounding the region of the brain necrosis, it has been speculated that ADAM12 might facilitate GBM cells to attach to the reactive astrocytes present near the leading invasive edge or, alternatively, it might be involved in mutual cell attachment and spreading of GBM cells to form tumor cell aggregates that are commonly observed in human GBM during the invasive growth [27].