The morphological transformation and cessation of proliferation in RNAi-transduced cells suggested that NTera-2 cells might undergo a process of differentiation. To further verify that these changes were accompanied by differentiation toward an astrocyte-like lineage, cells were examined for the expression of astrocytic markers. The intermediate filament protein, GFAP, is considered a cell type-specific marker for astrocytes. GFAP expression was observed in differentiated cells examined by immunofluorescence and Western blot assays (Fig. 1D) . Another astrocyte-specific marker, glutamine synthetase (GS) [41] , was also detected by immunofluorescence and Western blot assays in differentiated cells (Fig. 1E ). In addition, we detected neither the oligodendrocyte markers, A2B5 [42] and Gal-C [43] , nor the neuron-specific markers, MAP-2 and Pax6 [44] , after 21 days of transduction (Fig. S1C) . Taken together, these differentiated NTera-2 cells produced by our newly developed protocol had an astrocyte-like morphology and expressed the astrocyte-specific markers, GFAP and GS, suggesting differentiation toward an astrocytic lineage. Therefore, these differentiated cells distinctly differed from previous reports of a mixture of different neuronal cell types after retinoic acid induction [35] .