In an integrative approach we are trying to elucidate the function of novel regulators of the developing mouse nervous system as well as adult neural stem cell’s biology. Neural stem cells (NSCs) are not only present during embryonic brain development but persist in the adult brain in two specialised niches: the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus. A translational state array analysis (TSAA) has been used for identification of factors that might be essential for embryonal/adult-stem cell’s biology. Using lentiviral approaches and “in utero”- electroporation the function of identified targets during neuronal development and in the adult neurogenic niches will be examined. Defective regulation of some of these factors can contribute to tumor formation.