K13-induced NF-κB activity is critical for the activation of CCL20 promoter. (A) The 293T cells were transfected with an empty vector or the indicated vFLIPs (250 ng/well) along with a WT CCL20 promoter luciferase construct (75 ng/well) and a pRSV/LacZ (β-galactosidase) reporter construct (75 ng/well), and the reporter assay performed as described in “Luciferase reporter assay.” The values shown are averages (mean ± SE) of 1 representative experiment of 3 in which each transfection was performed in duplicate. (B) Ectopic expression of WT K13 but not its NF-κB–defective mutants (K13 58AAA and K13 67AAA) induces CCL20 promoter activity. The experiment was performed essentially as described in panel A. (C) The NF-κB site in the CCL20 promoter is critical for activation by K13. The 293T cells were transfected with a control vector or a vector encoding K13 along with either CCL20-WT-Luc or CCL20-ΔNF-κB-Luc reporter constructs, and the luciferase reporter assay performed as described in panel A. The values shown are averages (mean ± SE) of 1 representative experiment of 3 in which each transfection was performed in duplicate.