For example, using a Cre-inducible mouse model of glioblastoma, Chen et al. found that Nestin+-marked adult neural stem cells genetically labeled with green fluorescent protein (GFP) made up only a small fraction of a naïve tumor, but, upon treatment with temozolomide, an alkylating agent that is used to treat some brain cancers, these cells and their progeny expanded to become the most abundant tumor clone (Chen et al., 2012). The gene discussed is NES; the disease is neoplasm.