(A) Four individual sequences of siRNA guide strands targeting PPIB mRNA, color-coded blue, black, yellow and green; (B) Comparison of silencing activity across the siRNA sequences. The bars present activity of the modified guide strand (Gn) minus activity of the unmodified control (G0) divided by one minus activity of the unmodified control (G0): Y = (YGn – YG0)/(1 – YG0). After the normalization, zero on the Y-axis is the activity of unmodified siRNAs, a negative value indicates an activity of amide-modified siRNA that is higher than that of unmodified siRNA, while ‘1’ indicates complete loss of activity. The positions of amide linkages are numbered based on the 5′-nucleotide, e.g. G1 has an amide between N1 and N2.