RB1 and glioblastoma: The research in this field is based on the evidence that the deregulation of three main pathways have been highlighted in GBM, namely the receptor tyrosine kinases (RTKs)/Ras/PI3K pathway (altered in 88% of GBM patients), the p53 pathway (altered in 87% of GBM patients), and the retinoblastoma (RB) protein pathway (altered in 78% of GBM patients) [17].