Meanwhile, the expression of astrocytic sphingosine-1 phosphate receptor 3 (S1P3) in tumor cells could trigger astrocytes to secrete interleukin (IL)-6 and C–C motif chemokine ligand (CCL)-2, promoting endothelial cell adhesion dissolution and thus increasing BBB permeability [58]. The gene discussed is CCL2; the disease is neoplasm.