GDF15 and brain neoplasm: In silico analyses using GlioVis (http://gliovis.bioinfo.cnio.es/)23 evidenced a positive correlation between the expression of CCL2, GDF15 and ANG (angiogenin) and the CNS WHO grade of the brain tumors (Supplementary Fig. 2a); conversely, a negative correlation was found between ZBTB18 and CCL2 (r = −0.50, p = 0.00) and GDF15 (r = −0.62, p = 0.00) (Supplementary Fig. 3a, c).