Moreover, the study from our group also found that densely plated normal astrocytes but not tumor sphere glioma cells downregulate genes in the cholesterol biosynthetic pathway including farnesyl diphosphate synthase, farnesyl-diphosphate farnesyltransferase 1, and squalene epoxidase, (FDPS, FDFT1, and SQLE, Figure 3) [71]. This evidence concerns the gene FDPS and central nervous system cancer.