Cloning IKKγ (amino acids 150-272 and full length) was subcloned into pETM442 that was derived from pET44b(+) (Novagen). ks-vFLIP was subcloned into pETM6T1, also derived from pET44b(+). The original pET44b(+) vector was modified by deletion of the S-tag, thrombin and enterokinase recognition sequences that were replaced by a single TEV cleavage site followed by either Nhe1, Nde1 or Nhe1, Nco1 restriction sites to produce pETM442 and pETM6T1 respectively. The IKKγ inserts were subsequently cloned into the EcoR1 and BamH1 sites to produce a 6His-NusA-6His-(TEV site)-IKKγ(150-272) (or 6His-NusA-6His-(TEV site)-IKKγ(1-419)) fusion protein that after cleavage with TEV protease had the sequence GHMASGS N-terminal to the first amino acid (pETM442-IKKγ(150272) or pETM442-IKKγ(1-419)). The same strategy was used for production of ks-vFLIP (1-178) where a similar 6His-NusA fusion protein was produced that after TEV cleavage had an additional GAMGS sequence immediately N-terminal to the ks-vFLIP protein (plasmid pETM6T1-vFLIP(1-178)). For the pull down assays, IKKγ(150-272) was cloned into a pRSF duet vector (Novagen) to generate a non-cleavable 6His-tagged construct (plasmid pRSF6HisIKKγ(150272)).