TNF and cancer: Astrocytes transform to support cancer survival, for example through the release of PEA-15 (the phosphoprotein enriched in astrocytes of 15 kDa [53]) or CCL20 (the chemokine C–C motif ligand 20 [54]), and cancer invasion through the release of cytokines such as TNF- α [55], IL-6 and IFN-γ, through the activation of the nuclear factor kappa B (NF-κB) and the transforming growth factor-β (TGF-β) signaling pathways [56].