Nuclear export of olig2 and STAT3 activation during cell differentiation Oligo 2 is a basic HLH transcription factor, and its expression in the nucleus is required for oligodendrocyte development by preventing the formation of the STAT3 and p300 complex in the nucleus [45, 46] . To confirm the cellular differentiation of NTera-2 cells, we examined the expression of olig2 and found that olig2 was expressed in nuclei of undifferentiated NTera-2 cells (Fig. 2A) . During specification for an astrocyte-like lineage, there was a striking translocation in the distribution of olig2 from nuclei to the cytoplasm ( Fig. 2A) . Thus, the translocation of olig2 from nuclei may suggest activation of STAT3 in nuclei. Therefore, we analyzed the phosphorylation status of STAT3 and found that there was significant accumulation of phosphorylated STAT3 in differentiated cells compared to undifferentiated cells (Fig. 2B) . Furthermore, specific antibodies against STAT3 were found to have co-immunoprecipitated p300 in differentiated cells, but not in undifferentiated cells, suggesting specific formation of STAT3-p300 complexes in differentiated cells (Fig. 2C) . These findings suggest activation of the STAT3 signaling pathway during the differentiation of NTera-2 cells.