A. CYLD knockdown by siRNA-CYLD markedly reduced expression of CYLD and enhanced NTHi-induced NF-κB-dependent promoter activity in HMEEC cells. B, overexpression of WT-CYLD inhibited NTHi-induced NF-κB-dependent promoter activity in HMEEC cells. C, NTHi-induced DNA binding activity of NF-κB was enhanced by CYLD knockdown, as assessed by EMSA. D, CYLD knockdown by siRNA-CYLD enhanced NTHi-induced IL-1β and IL-8 expression at mRNA level in HMEEC-1 cells. E, TRAF7 synergistically enhanced TRAF6-induced NF-κB-dependent promoter activity. Overexpression of WT-CYLD inhibited TRAF6- and TRAF7-induced NF-κB-dependent promoter activity, whereas CYLD knockdown by siRNA-CYLD enhanced TRAF6- and TRAF7-induced NF-κB-dependent promoter activity in lung epithelial A549 cells. *p<0.05, compared with NTHi-inoculated in Mock in A, B and D. Values are means ± S.D. (n = 3).