Western blot showing Ago3 immunopurified from BmN4 cells before (Control) and after Siwi knockdown (Siwi KD). 32P-labeling of RNAs isolated from Ago3 (a mixture of unphosphorylated and phosphorylated) immunopurified from Siwi-depleted cells. 15-20-nt RNAs (indicated by a black line) were isolated and sequenced. 