PDGFRA and glioblastoma: Higher levels of choline, and its derivatives (phosphocholine and glycerophosphocholine) are observed in GBM cells characterized by high levels of Platelet-Derived Growth Factor Receptor alpha (PDGFRA) and low levels of Epidermal Growth Factor Receptor (EGFR) [39], whereas higher levels of aspartate, citrate, glutamine and glutamate correlate with the over-expression of genes for some transporters, such as Solute Carrier Family 38 member 1 (SLC38A1), Solute Carrier Family 7 member 8 (SLC7A8), and Solute Carrier Family 1 Member 1 (SLC1A) [39].