RB1 and glioblastoma: A TCGA study of 1,122 patients, identifying genomic alterations in GBM, indicates that a majority of tumors harbored aberrations in each of these signaling networks (the Rb network in 79%, RTK/Kras/PI3K/PTEN network in 90%, p53 network in 86% and all three networks in 74% of GBMs analyzed) (2).