Because IKKα is a member of the IKK complex and because siRNA targeting of IKKα in KRAS positive cells also reduces NF-κB activity and inhibits IκBα phosphorylation/degradation (Supplementary Fig. S1 and Fig. 1C), it is important to determine the contribution of this kinase to the proliferative phenotype of KRAS positive/p53 null lung cancer cells. This evidence concerns the gene TP53 and lung cancer.