In the 4DFG (25 mg/kg)-treated group (n = 8), the post-injection peak concentration of the drug should be near 2.5 mM, a concentration in the physiological range of serum Gal, and at this concentration, they will be able to saturate the galactose-scavenging enzymes of the glioma cells. This evidence concerns the gene GAL and central nervous system cancer.