Correlation of GPR158 expression levels to GBM, stratified according to the molecular subtypes [4] further supports this notion, as GPR158 expression is highest in the proneural subtypes (a class that is enriched for IDH mutations and PDGFR amplifications), and decreases in classical (enriched for EGFR amplified and CDKN2A mutant tumours) and mesenchymal subtypes, which are most commonly NF1 mutated (Supplementary Figure 3c). Here, IDH1 is linked to glioblastoma.