GM-CSF induces neuronal differentiation of adult neural stem cells. A, Expression of neural markers in stem cells. 3d after GM-CSF treatment of adult neural stem cells, the upregulation of the neuronal markers β III-tubulin and NSE (neuron specific enolase) was measured by qPCR. Note that there is significant induction of β III-tubulin (*, p<0.05, two-tailed t-test) whereas regulation of PLP or GFAP was not detectable. B, GM-CSF drives concentration-dependent neuronal differentiation of NSCs. For the luciferase reporter assay, adult neural stem cells were transfected with the pGL3-p-βIII-tubulin reporter vector and stimulated with increasing concentrations of GM-CSF. 48 h after stimulation, a concentration-dependent activation of the βIII-tubulin promoter was detected. As positive control, NSCs were treated with the standard differentiation protocol involving withdrawal of EGF and bFGF, and addition of FCS (*, p<0.05 by ANOVA and Newman-Keuls post-hoc test). C, Analysis of neuronal differentiation on the cellular level. FACS analysis demonstrating stem cells positive for the neuronal marker MAP-2 after treatment with GM-CSF. The percentage of MAP-2-positive cells is doubled under GM-CSF treatment (*, p<0.05, two-tailed t-test). All data are shown as mean ± SEM.