The inside cover picture shows how siRNAs modified with North bicyclo[3.1.0]hexane 2′-deoxy-pseudosugars are able to activate the RNA interference machinery. The paper confirms that the North conformation is critical for RNAi activity. For further details, see the Full Paper by R. Eritja et al. on p. 1056 ff. Illustration: Montserrat Terrazas.