Unmodified and modified RNA aptamers compete with κB DNA duplex. (A) Labeled κB DNA duplex was incubated in the absence of NF-κB (lane 1), in the presence of NF-κB (lane 2), or together with various unlabeled competitors (lanes 3–6 for RNA3, lanes 7–10 for thioRNA4, lanes 11–14 for thioRNA5). Triangles indicate increasing unlabeled competitor concentrations (0.01, 0.1, 1 and 10 μM). (B) Quantitation of competitive inhibition of κB DNA duplex binding. Error bars reflect standard deviation from three independent experiments. Binding data are presented as values relative to the level of labeled κB DNA duplex binding in the absence of competitor.