PKM and cancer: For instance, mutually exclusive alternative splicing of the PKM pre-mRNA generates either an exon 9 inclusion isoform PKM1, or an exon 10 inclusion isoform PKM2. Through upregulation of heterogeneous nuclear ribonucleoproteins (hnRNPs) that repress PKM exon 9 inclusion, cancer cells express high level of the PKM2 isoform to maintain aerobic glycolysis3.