We screened 25 WHO I and II astrocytomas for mutations of PTPN11, NRAS, KRAS, and HRAS genes and identified the somatic G12A KRAS mutation in one pilocytic astrocytoma.
Combined expression of IGFBP2 or Akt with K-Ras was required to form astrocytomas, indicating that activation of two separate pathways is necessary for gliomagenesis.