Based on studies with the rat protein whose amino acid sequence is 93% identical to the human protein, NPAS4 possesses an overlapping nuclear localization signal (NLS) and a nuclear export signal (NES) in its basic-helix-loop-helix (bHLH) domain, two putative NLSs and one NES in its PAS-2 domain, and two active NESs that overlap with a putative NLS in its C-terminus (Greb-Markiewicz et al. 2018). NPAS4 mainly localizes to the nucleus, but a small portion is also present in the cytoplasm and intracellular membranes (Shamloo et al. 2006, Sullivan et al. 2016). Cytoplasmic export of NPAS4 is dependent on XPO1 (Exportin-1) (Greb-Markiewicz et al. 2018).