SHH and central nervous system cancer: The importance of microglia in pediatric glioma research has been highlighted by the results of several clinical studies.117–119 Immature microglia in the cerebellum and corpus callosum exhibit high levels of insulin-like growth factor, promoting the expansion and survival of neural precursor cells in sonic hedgehog (SHH)-subtype medulloblastoma.117 Myeloid cells from mature murine SHH medulloblastoma models enhanced tumor cell killing.117 This leads to the implication that microglia can assume anti- or pro-tumor phenotypes based on their level of maturation.