GFAP and central nervous system cancer: Simultaneously, the astrocyte/glioma marker GFAP and the malignancy marker CD44 dramatically expressed upon serum stimulation with higher levels, but those of the neuron marker Tuj1 were not (Fig. 1B c–e, Fig. 1C, and Fig. S1B), demonstrating that the GIC clones had both the characteristics of NSCs and the capacity to differentiate into glioma cells, and that they were also capable of long-term self-renewal, differentiation, and tumorigenesis.