POPDC3 and glioblastoma: The role of the remaining genes in the risk model, POPDC3 (Popeye Domain Containing 3), PTPRN2 (Protein Tyrosine Phosphatase Receptor Type N2), and SLC46A2 (Solute Carrier Family 46 Member 2,) in GBM remains largely unknown, though each has been found to be potential biomarkers in other types of cancer [52,53].