The increase of expression of CD15, a marker of brain tumor stem cells, detected by qRT-PCR in the Ptch1+/−/Btg1KO MBs compared with Ptch1+/−/Btg1WT MBs (Figure 7A), was confirmed at protein level by immunohistochemical analysis of tumor sections from MBs of the two different genotypes under study (Figures 7C,D). The gene discussed is FUT4; the disease is brain neoplasm.