A previous study analyzing GBM tumor tissues revealed that genes involved in RTK (receptor tyrosine kinases) signaling, PI3K (phosphoinositide 3-kinase) signaling, MAPK (mitogen-activated protein kinase) signaling, and p53 and RB1 (retinoblastoma gene) signaling pathways were frequently mutated in GBM tumor cells, suggesting that dysfunction of these pathways may be largely associated with GBM31,33. Here, RB1 is linked to neoplasm.