Effect of ODN backbones and CpG motif on NF-κB activation. (A) 293XL-hTLR9 cells transfected with hTLR9-signaling reporter plasmid were stimulated by PD-ODN2006 and PTO-ODN2006 with various concentrations. n = 3, mean (sd). Statistical significances are denoted as follows: *P < 0.05, **P < 0.01. (B) Stability of PD-ODN2006 and PTO-ODN2006 in aqueous solution with/without serum. The arrow indicates PTO-ODN-protein complex. (C) PD-ODN2006 and PNA-ODN2006 (0.2 μM) were applied to cells with/without LyoVec. n = 3, mean (sd). Statistical significances are denoted as follows: *P < 0.05, **P < 0.01. (D) 0.1 μM of PTO-ODN2006 mutants (1: PTO-ODN2006, 2: PTO-ODN2006-GC, 3: PTO-ODN2006-1GC, 4: PTO-ODN2006-2GC, 5: PTO-ODN2006-3GC, 6: PTO-ODN2006-4GC, 7: PTO-ODN2006-2,3,4GC, 8: PTO-ODN2006-2,3GC, 9: PTO-ODN2006-2,4GC, 10: PTO-ODN2006-3,4GC) were applied to cells. n = 3, mean (sd). All P values are shown relative to the PTO-ODN2006, *P < 0.05, **P < 0.01.