It has been hypothesised that the cytotoxic activity of TMZ is mediated through reactive O6-methylguanine in DNA (Tisdale, 1987); thus, inhibition of O6-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein at the O6-guanine position, may increase the cytotoxicity of TMZ against neuroblastomas (Wagner et al, 2007b). Here, MGMT is linked to neuroblastoma.