PDGFA and glioblastoma: Finally, we interrogated the the cancer genome atlas GBM reverse phase protein array database and found that high PDGF-A–expressing GBMs have statistically significant lower levels of phospho-S6K T389 (P = 0.0006) and trending lower levels for phospho-4EBP1 S65, RPS6 S235/236, S240/244, and p90RSK T359/363 (Fig 6F).