FIGURE 2.

Introduction of single deoxynucleotides does not affect siRNA activity. (A) EGFP expression of HeLa cells transfected with siRNAs that contain single deoxynucleotides within the sense strand (I), the antisense strand (II), and both strands (III) determined by measuring fluorescence intensity. EGFP fluorescence intensity was normalized to that of RFP. Fluorescence intensity of a sample that was not treated with siRNA (no RNA) was set to 100%. The down-regulation of EGFP expression in a positive control sample transfected with a commercially available siRNA was assumed to be the maximum available one. From the figure it can be seen that down-regulation of the deoxynucleotide-containing siRNA sequences (I–III) is as effective as the one of the positive control (siRNA). (B) Sequences of the siRNA strands used. The positions of the deoxynucleotides are marked in gray.