NFKB1 and lung cancer: The unregulated NF-κB signaling might be due to the dysfunction of IKK, an upstream kinase for the phosphorylation of IκB and the subsequent proteasomal degradation, in such lung cancer subpopulation where the IκB level is relatively high and the phosphorylation of IκB cannot be induced on pemetrexed stimulation (figure 4E and online supplemental figure S4B).