Relative expression (normalized with RNU6B and relative to NT) of piR-32051, piR-39894 and piR-43607 in ACHN cells by small RNA quantitative RT-PCR when miRNA-related genes were knocked down. All expression levels shown were normalized with RUN6B and are relative to those of NT). NT, no treatment; siNC, transfected with scrambled anti-sense RNA molecules for negative control; siAgo1, siAgo2, siAgo3, siAgo4, siDrosha and siDicer, trans-fected with anti-Ago1, Ago2, Ago3, Ago4, Drosha and Dicer1 siRNA molecules, respectively.