miRSystem: an integrated system for characterizing enriched functions and pathways of microRNA targets. miRSystem is a database which integrates seven well known miRNA target gene prediction programs: DIANA, miRanda, miRBridge, PicTar, PITA, rna22, and TargetScan. This database contains validated data from TarBase and miRecords on interaction between miRNA and its target genes. Several new features which distinguish miRSystem from others: 1) miRSystem allows querying multiple miRNAs in one step for the associations between the miRNAs and their target genes. 2) Two algorithms are incorporated to characterize the enriched biological functions/pathways among the genes targeting by queried miRNAs.