Reduction of IKKα expression promotes UVB skin carcinogenesis in mice. A: Skin tumor incidence in Ikkα+/+ (+/+) and Ikkα+/− (+/−) mice (P < 0.001, COX proportional hazards model). IKKα protein levels were detected by Western blotting. β-Actin, loading control. NS indicates nonspecific band. B: Tumor multiplicity in Ikkα+/+ and Ikkα+/− mice (P < 0.001, Poisson regression analysis). C: Tumor numbers in 33 Ikkα+/+ and 29 Ikkα+/− mice at week 28. D: Weight comparison of tumors found in 33 Ikkα+/+ and 29 Ikkα+/− mice (P < 0.05, t test). Lines indicate means; g, Gram (tumor weights).