To control for the possible effects of genetic background on glioma phenotype observed, we also generated GlastCreERT2;Ascl1GFP/+;Nf1F/F;Tp53F/F and GlastCreERT2;Ascl1F/+;Nf1F/F;Tp53F/F mice in parallel for comparison, both of which developed tumors that are still heterozygous for Ascl1 when induced with tamoxifen, and are referred to as Ascl1HET tumor mice. The gene discussed is ASCL1; the disease is central nervous system cancer.