Effect of novel CpG-ODNs on NF-κB activation in 293XL-hTLR9 cells and 293XL-null cells. (A) 293XL-hTLR9 cells transfected with hTLR9-signaling reporter plasmid were stimulated by PD-ODN with an elevated number of CpG motifs. n = 3, mean (sd). All P values are shown relative to the PD-ODN2006 with the same concentrations, *P < 0.05, **P < 0.01. (B) Stability of PD-ODNs in aqueous solution with/without serum. The arrow indicates supramolecular structure of PD-ODN2006-G5. (C) NF-κB activation by PD-ODNs (1: PD-ODN2006, 2: PD-ODN2006-2006, 3: PD-ODN2006-2006-2006, 4: PD-ODN2006-G5, 5: PTO-ODN2006) in hTLR9 deficient cells (293XL-null) and hTLR9 expressing cells (293XL-hTLR9 cells). Statistically significant results are denoted as follows: *P < 0.05, **P < 0.01.