PKM and cancer: Pyruvate kinase M2 (PKM2), the embryonic splice variant re-expressed in cancers, exhibits dynamic oligomeric regulation: tetrameric forms catalyze phosphoenolpyruvate-to-pyruvate conversion, whereas dimeric PKM2 translocates to the nucleus, serving as a transcriptional coactivator for HIF-1α, signal transducer and activator of transcription 3 (STAT3), and β-catenin to drive cell cycle progression and stemness (37, 88–94).