One mutant has a single nucleotide insertion that converts the A bulge at the Dicer site to an AU pair, while the other has two single nucleotide insertions such that replaced both A bulges with AU pairs. Both mutated targets are properly processed, however C1 is unable to inhibit Dicer processing of either mutant (Fig. ). These data support that C1 targets the Dicer site, as designed, to inhibit processing.