Novel functions for small RNA molecules.

Small RNAs are short (approximately 18 to 30 nucleotides), non-coding RNA molecules that can regulate gene expression in both the cytoplasm and the nucleus via post-transcriptional gene silencing (PTGS), chromatin-dependent gene silencing (CDGS) or RNA activation (RNAa). Three classes of small RNAs have been defined: microRNAs (miRNAs), siRNAs and Piwi-interacting RNAs (piRNAs). Research has indicated that small RNAs play important roles in...