It has been shown that 18F-FDG uptake correlates with tumor size, tumor risk grade, and expression levels of glucose transporter 1 (GLUT1), hexokinase 1 (HK1), and lactate dehydrogenase A (LDHA), with GLUT1, HK1, pyruvate kinase (PKM2), and LDHA expression increasing with higher tumor risk grade16. The gene discussed is PKM; the disease is neoplasm.