PTEN and glioblastoma: For example, the epidermal growth factor receptor (EGFR) activation increases the transcription of VEGF via the PI3K pathway, but not dependently on HIF-1, in glioblastoma cells; moreover, the EGFR amplification has an additive effect with a PTEN loss of function in increasing the VEGF levels, by enhancing the VEGF promoter activity [98,99].