Sequential labelling using EdU and BrdU.

<p>Microscopy pictures of cells double-labelled with EdU and BrdU. Cells synchronized in G1 phase were released and pulse-labelled in two consecutive S-phases, first with EdU, then with BrdU, as described in the text. Samples were harvested after the next mitosis, fixed and processed as described and imaged using fluorescence microscopy. Negative controls for cross-reactivity are provided on <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088629#pone.0088629.s003" target="_blank">Fig. S3</a>.