Despite findings from studies investigating the sensitivity of GBM-SCs to chemotherapy result inconclusive, with some reports describing an increased resistance (Eramo et al., 2006) and others an increased susceptibility (Beier et al., 2008), all studies reported an overall increased resistance to temozolomide of MGMT-expressing GBM-SCs (reviewed in Beier et al., 2011). Here, MGMT is linked to glioblastoma.