Correction to: Nature Materials https://doi.org/10.1038/nmat3361, published online 1 July 2012.

In the version of this Article originally published, in Fig. 2b it was wrongly indicated that the left and right H&E stained images for the 3D B16-F1 group were taken from two distinct experimental mice. These representative images are in fact taken from the same mouse. Similarly, for the control group, both images are taken from the same mouse. H&E images from all of the individual mice in each group in Fig 2a are present in the updated Supplementary Information.