Nature Communications 1, Article number: 134 (2010); Published: 7 December 2010; Updated: 7 February 2012

This Article contains two typographical errors in the first paragraph of the Results section. The phrase ‘decreases from 12 Pa to less than 14 Pa’ should read ‘decreases from 12 Pa to less than 4 Pa’ and ‘a continuous decrease of the linear stiffness to 12 Pa’ should read ‘a continuous decrease of the linear stiffness to 2 Pa’.