The Positives and Negatives of NPR: A Unifying Model for Salicylic Acid Signaling in Plants
Salicylic acid (SA) is a potent inducer of defense gene expression in plants, but how SA activates transcription has been controversial. In this issue of Cell, Ding et al. show that the SA-binding proteins NPR3 and NPR4 function as transcriptional co-repressors, with this activity being blocked by SA.