CCL2 and glioblastoma: Through binding to IL-1R present on the surface of GBM cells, IL-1 can promote the cascade of the MAPK and p65 signaling pathways, resulting in the production of proteins and soluble forms of VCAM-1 and ICAM-1, which enhance monocytes adhesion and secretion of CCL2 and IL-6 through activated macrophages.