The cell lines studied included wild-type and four genetically modified mouse astrocyte lines with different levels of cancerous mutations, including single tumor suppressor gene mutation (p53−/−), double tumor suppressor gene mutations (p53−/− PTEN−/−), single tumor suppressor gene with oncogene mutation (p53−/−Braf), and double tumor suppressor with additional oncogene mutations (p53−/− PTEN−/− Braf). This evidence concerns the gene PTEN and neoplasm.