Length signature of endo-siRNAs that co-localize with RNAPII or co-precipitate with AGO 1. (A) Total endo-siRNA sample excluding reads that map to LPPR5, LYPD3 or TMEM25, as discussed in the text. (B) Endo-siRNA signature of all reads that do (left) or do not (right) co-localize with RNAPII as indicated by the Venn diagram. (C) Same as (B) but reads that mapped to regions with low RNAPII ocupancy (<1.5 percentile) were excluded, low stringency. (D) Endo-siRNA length distribution of reads that do (left) or do not (right) associate with AGO1. The rust-colored reads stem from a single gene, STAMBP.