We examined the ispinesib sensitivity of two proneural murine GBM lines derived from genetically engineered mouse models (GEMMs)—one deleted for Trp53, and the other co-deleted for Trp53 and Pten, referred to as Trp53−/− and Trp53/Pten−/−, respectively (Lei et al., 2011). This evidence concerns the gene TP53 and glioblastoma.