HK2 and colorectal carcinoma: The enzyme pyruvate kinase (PK) is crucial for glycolysis (147), with the altered form PKM2 (PK muscle isozyme 2) (148, 149), increased lactate production, and the upregulation of glucose transporter 1 (GLUT1), Hk2, and other glycolytic enzymes being reported in CRC (150–152).