13. Which description about glucose metabolism in tumor is not true? (A) Cancer cells use energy-inefficient glycolysis under adequate oxygen supply. (B) GLUT2(Glucose transporter type 2) is a predominantly expressed isoform in most common cancers. (C) Conversion of pyruvate into lactate is markedly increased. (D) Aerobic glycolysis allows cancer cells to meet the requirements of generating enough ATP and biosynthetic precursors.