PTBP1 and glioblastoma: Importantly, the proto-oncogene c-MYC was shown to orchestrate the concomitant up-regulation of PTBP1 and two other hnRNPs (hnRNPA1, hnRNPA2) in GBM [45], which cooperate in the splicing regulation of the pyruvate kinase gene (PKM) [45,46] (Table 2).