CCL2 and glioblastoma: Additionally, for T lymphocytes, GSCs play a direct role in inhibiting the proliferation and activation of T cells and inducing T cell apoptosis, which may be mediated via the inhibitory, co-stimulatory molecule B7-H1, soluble factors such as galectin-3, the T cell chemokine attractants VEGF, chemokine (C-C motif) ligand 2 (CCL2), and prostaglandin E2 (202, 207–210), leading to silencing of the immune response and escape immune surveillance in GBM.