PTGER4 and glioblastoma: Interrogation of a publicly available collection of 71 GICs with DNA methylome and transcriptome datasets (HGCC) identified 34% of cultures displaying high methylation/low expression of PTGER4 as compared to cohort average, as well as 21 and 22.5% low expression/high methylation of NTRK2 and ALDH3B1 respectively, raising the possibility that these signatures could be widely shared among GBM patients (Fig. S8c).