Correction to: Nature Communications https://doi.org/10.1038/ncomms8389, published online 12 June 2015

In the version of the article initially published, there were errors in Supplementary Figs. 4b and 6a. In Supplementary Fig. 4b, the cell invasion image for guanosine, EV was inadvertently duplicated from GTP, EV. In Supplementary Fig. 6a, the western blot for DCK under BT549 was inadvertently duplicated from DCK under MDAMB231. The corrected Supplementary Figs. 4, 6 and raw data for Supplementary Fig. 6a are included as Supplementary Information alongside this amendment. Due to the age of the article, the article cannot be updated directly; this notice serves to correct the article.