NF1 and astrocytoma (excluding glioblastoma): The generation of Pten CNS heterozygotes in these Nf1/Trp53 double knockout mice led to the formation of high-grade astrocytomas, while Pten haploinsufficiency led to the formation of grade 3 astrocytomas, and the Pten loss of heterozygosity (LOH) along with Akt activation-accelerated progression into grade 4 astrocytomas [70].