Additionally, murine models of NF1-associated OPG have provided relevant information regarding the role of microenvironment on tumor growth, and particularly of microglia, immune system-like non-neoplastic cells which, unlike glioma cells that undergo loss of heterozygosity (NF1−/−), maintain the heterozygous state (NF1+/−). Here, NF1 is linked to central nervous system cancer.