The transcription factor Sox
2 is one of the earliest determinants of the neural system in vertebrate and plays crucial roles in stem cell maintenance. Through bioinformatical analysis, we found that the 3'untranslated regions (3'UTR) of vertebrate Sox
2 mRNAs (especially the 300 bases at the most 3' end) are highly conserved and contain four conserved AU rich fragments. Through reporter gene analysis, we evaluated the effects of the Sox
2 full length 3'UTR and the conserved fragments on gene expression in Xenopus laevis
embryos and cultured cells. The results showed that the conserved fragment 2 from the 3'UTR of Xenoups laevis Sox
2 was able to increase the reporter gene expression significantly, indicating the possibility that the expression level of Sox
2 might be regulated post-transcriptionally through its 3'UTR.