Enhancers play a crucial role in gene regulation but the participation of 
enhancer transcripts (i.e. enhancer RNA, eRNAs) in regulatory systems remains 
unclear. We provide a computational analysis on eRNAs using genome-wide data 
across 12 mouse tissues. The expression of genes targeted by transcribing 
enhancer is positively correlated with eRNA expression and significantly higher 
than expression of genes targeted by non-transcribing enhancers. This result 
implies eRNA transcription indicates a state of enhancer that further increases 
gene expression. This state of enhancer is tissue-specific, as the same enhancer 
differentially transcribes eRNAs across tissues. Therefore, the presence of 
eRNAs describes a tissue-specific state of enhancer that is generally associated 
with higher expressed target genes, surmising as to whether eRNAs have gene 
activation potential. We further found a large number of eRNAs contain regions 
in which sequences and secondary structures are similar to microRNAs. 
Interestingly, an increasing number of recent studies hypothesize that microRNAs 
may switch from their general repressive role to an activating role when 
targeting promoter sequences. Collectively, our results provide speculation that 
eRNAs may be associated with the selective activation of enhancer target genes.