Given the wide expression of ATF5 in human glioblastomas and lower grade gliomas and the variety of human and rodent-derived glioblastoma cell lines (with and without compromised p53 and PTEN) that express and require ATF5 for survival [3, 4, 6, 7], it seems likely that a range of malignant glioma cell types will be susceptible to cell-penetrating d/n-ATF5. This evidence concerns the gene PTEN and central nervous system cancer.