BDNF and glioblastoma: Figure 2 shows a heat map with fold changes described in the supplementary table [Additional File 4], revealing four cytokines and growth factors in all three GBM-M2 lines, GM-CSF, IL-6, BDNF, and IL-8 that were highly elevated in GBM-M2 cells (DBM2, U87-M2 and U251-M2) compared to their parental cell lines (DBTRG-05MG, U87 and U251).