National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA. shabalin@ncbi.nlm.nih.gov
For decades, researchers have focused most of their attention on protein-coding genes and proteins. With the completion of the human and mouse genomes and the accumulation of data on the mammalian transcriptome, the focus now shifts to non-coding DNA sequences, RNA-coding genes and their transcripts. Many non-coding transcribed sequences are proving to have important regulatory roles, but the functions of the majority remain mysterious.