Initiation and amplification of SnRK2 activation in abscisic acid signaling

SnRK2 kinase activity is rapidly activated in response to ABA. Here the authors show that initial activation of SnRK2s is achieved by B2 and B3 RAF kinase-mediated phosphorylation of the activation loop and that transphosphorylation between SnRK2s then amplifies the response.