Our previous cDNA microarray data for the expression of some ABC transporter genes (available in NCBI GEO repository #GSE72431) reveal that only ABCB1 gene is specifically upregulated in C6 glioma SP cells compared with MP cells approximately by 10.6-fold (SP:MP = 0.64:0.060), suggesting that the ability of SP cells to expel xenobiotics is mainly dependent on ABCB1 in C6 cells [25, 26]. This evidence concerns the gene ABCG2 and central nervous system cancer.