Ferritin has been described to play a role in cellular differentiation, and experiments with rat glioma cells have found a regulatory effect of insulin on its transcription.21 Ferritin levels can be elevated in CSF and in serum of glioblastoma patients, and the protein was detected immunohistochemically in glioblastoma tissue.10,, 22. This evidence concerns the gene INS and glioblastoma.