Renewing the assault on mRNA.

Mammalian cells dislike double-stranded RNA. They interpret it as a sign of an intruder, and they can unleash a recently discovered defensive mechanism to deal with the problem - they chop the invader into little pieces and use the remnants, called small interfering RNA, to identify and destroy the invader and its progeny. This process, known as RNA interference, may lend itself to new treatments for a wide range of diseases. RNA interference, however, resembles two therapies studied during the 1990s, antisense and ribozymes, in that the gene-silencing target is messenger RNA (mRNA). Is RNA interference really the Next Big Thing - or just a variation on an older but still intriguing theme?