Figure 1: The molecular pathogenesis of human astrocytomas is depicted, with their origin from normal astrocytes. The progression from a grade III (anaplastic astrocytoma) to a highly-malignant glioblastoma multiforme is characterized by loss of PTEN/MMAC and other putative tumor suppressor genes on chromosome 10 and amplification of the EGF-R gene. The question mark (?) refers to those patients who present at initio with glioblastoma multiforme; whether these tumors progress through each step of this progression (either very rapidly or in a subclinical state) or skip various stages is not currently known.

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