Nature 505, 509–514 (2014); doi:10.1038/nature12940

In Extended Data Fig. 1 of this Article, the flow data presented in the ‘NL4-3 No Drugs’ panels were inadvertently duplicated in the ‘89.6 (X4/R5) No Drugs’ panels. A revised figure containing the corrected panels is now included as Supplementary Information to this Corrigendum. The conclusions of the experiment remain unchanged since the flow plots are nearly indistinguishable and the percentages reflecting the numerical events in each gate are accurate as stated. We apologize for not detecting and correcting this error before publication. We also would like to clarify that the flow data presented in Fig. 2d represents a sequence of three different cell separations using magnetic beads followed by three separate flow cytometric analyses of each cell preparation, as stated above the diagrams.