NFKB1 and lip and oral cavity carcinoma: 20 also found the same effect of Ins/Ins genotype on head and neck in an Indian population. This difference may be due to diverse genetic background and interactions with environmental factors such as betel nut chewing and smoking, which vary widely in different regions. Betel nut chewing has a very low prevalence in southeastern China, and smoking is the major risk factors for oral cancer in the area. Tobacco smoke could activate and up‐regulate the expression of NF‐κB in oral keratinocytes 21.