For example, Tanabe et al. [45] observed that TNF-α stimulation led to phosphorylation of STAT3 in rat glioma cells; however, the investigators did not evaluate the possible feed-forward mechanisms and concluded that TNF-α activated NF-κB, STAT3 and p38 MAPK, resulting in the production of IL-6. Here, IL6 is linked to central nervous system cancer.