Three putative miR-224 binding sites exist in the 3'UTR of NPAS4 mRNA, which is highly conserved (>95% identity between mouse, rat and human over 700 bp sequence). miR-224 was shown to downregulate expression from the NPAS4 3'UTR reporter and to downregulate human NPAS4 at both mRNA and protein levels (Bersten et al. 2014), suggesting that it forms an endonucleolytic RISC, although the existence of non-endonucleolytic miR-224 RISC has not been excluded. Expression of mouse Npas4 is downregulated by mouse miR-224 (Choy et al. 2017). In both the human and mouse genome, the miR-224 gene locus is found within the sixth intron of the GABRE gene on the X chromosome, which encodes the GABA receptor epsilon subunit. GABRE and miR-224 tend to be coexpressed (Bersten et al. 2014).