Bach2 is an oxidative stress-regulated transcription factor and functions as a repressor of gene expression directed by the TPA-response element, the Maf recognition element, and the antioxidant responsive element. To investigate the possibility that these enhancers are regulated in a tissue-specific manner, we analyzed expression of Bach2 during differentiation of neural cells. Bach2 was induced upon neuronal differentiation of P19 embryonic carcinoma cells, while its related factor Bach1 did not show significant change. By using affinity-purified anti-Bach2 antibodies, expression of Bach2 in mouse embryos was determined. High levels of Bach2 antigen were found in differentiating neuronal and lens cells in day 12.5 embryos. Consistent with the fact that subcellular localization of Bach2 is regulated by nuclear export in cultured cells, extensive Bach2-staining was found in the cytoplasmic regions of developing neuronal and lens cells. These results suggest that Bach2 regulates AP-1- and Maf-dependent gene expression during development of neuronal and lens cells and that its activity may be regulated by nuclear export in these cells.