Furthermore, microRNAs liberated in the brain tumor microenvironment are suppressive of PTEN, and loss of PTEN function is common in primary and metastatic brain tumors (24–33) and yields an actionable impairment in homologous recombination that predicts vulnerability to 3E10 (8, 16–19, 34–37). This evidence concerns the gene PTEN and brain neoplasm.