This mutually exclusive PKM splicing in cancer cells is controlled by three RBPs of the hnRNP family—PTBP1 (also known as hnRNPI), hnRNPA1, and hnRNPA2—that bind to splicing silencers flanking exon 9, preventing spliceosome recruitment to 5′ and 3′ splicing sites for exon 9. Here, PKM is linked to cancer.