IL6 and glioblastoma: In this model, three of four commonly used GBM lines were highly metastatic, grew more aggressively in the brain and, after two cycles (M2), expressed highly elevated levels of Interleukin-6 (IL6), Interleukin-8 (IL8) and granulocyte macrophage colony-stimulating factor (GM-CSF), thereby resembling GBM in patients [15-18].