PKM and cancer: The O-GlcNAcylation levels of PKM2 at Thr-405 and Ser-406 are increased in both cancer cells and patient tumors (28), which leads to the destabilization of the active PKM2 tetramer and the nuclear translocation of PKM2 to enhance the Warburg effect, while blocking this O-GlcNAcylation attenuates tumor growth in vivo (28).