Once selected some of them as possible candidates, i.e.; GPR3, GPR21, GPR22, GPR23, LPAR6/P2Y5 receptors, and after checking for their expression in cell lines, such as U87 and U873 glioma cell lines responsive to GBPs (Garozzo et al., 2010), we tested the effect of GBPs, namely GMP, GUO, and GUA, on the growth of U87 cells. This evidence concerns the gene GPR21 and central nervous system cancer.