Nat. Cell Biol. 14, 1336–1343 (2012); published online 25 November 2012; corrected after print 10 June 2015

In the version of this Letter originally published, a key funding source was omitted from the Acknowledgements. César Cárdenas's credit should have read 'C.C. was supported by the Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT) grant #1120443 and an award from the American Heart Association'.