In the letter by Wu et al. (Nature Cell Biol. 8, 398–406; 2006), the title was incorrect and should read as follows:

Sensing of Lys 63-linked polyubiquitination by NEMO is a key event in NF-κB activation

In the last paragraph of the main text, the second sentence should read as follows:

For example, ligation of the T-cell receptor (TCR) results in NF-κB activation through a molecular complex that includes Bcl10, Malt1 and CARMA1.

In the Methods, the ninth sentence in the Cell lines, Plasmids and Reagents section should read as follows:

Murine RIP was cloned into pGEX4T2 at the sites of BamHI and XhoI to produce GST–RIP.

These errors have been corrected online.