SLC2A1 and neoplasm: 18F-FDG accumulates in tumor cells via membrane glucose transporters (GLUT-1 and GLUT-3) due to abnormally increased glucose metabolism (18F-FDG can be phosphorylated by hexokinase and the product is more polar that can be trapped in the tumor cell, and the cellular concentration of 18F-FDG can be visualized by PET and represent the level of glucose metabolism) (12).