Just when scientists thought they had deciphered the roles played by the cell9s leading actors, a familiar performer has turned up in a stunning variety of guises. RNA, long upstaged by its more glamorous sibling, DNA, is turning out to have star qualities of its own. Science hails these electrifying discoveries, which are prompting biologists to overhaul their vision of the cell and its evolution, as 20029s Breakthrough of the Year. The online version of the Breakthrough of the Year section contains references and links not found in the print edition (see www.sciencemag.org/content/vol298/issue5602/#special).