PHGDH and glioblastoma: Two distinct binary classifications of IDH wild-type GBM tumors. GBM proteomic cluster 1 (GPC1) tumors exhibit Warburg-like features, neural stem cell markers, immune checkpoint ligands, and a poor prognostic biomarker, FKBP prolyl isomerase 9 (FKBP9). Meanwhile, GPC2 tumors show elevated oxidative phosphorylation-related proteins, differentiated oligodendrocyte and astrocyte markers, and a favorable prognostic biomarker, phosphoglycerate dehydrogenase (PHGDH).