As in the pathogenesis of the periodontal disease, the expression of cytokines, especially IL‐1β and TNF‐α, is initiated following the stimulation of bacterial lipopolysaccharide by NF‐κB, the role of a cellular pathway should include in vitro studies showing the effect of this molecular pathway on NF‐κB expression (Nichols et al., 2001). The gene discussed is TNF; the disease is periodontal disorder.