A plot of regions with large number of unmappable locations from STAT1 ChIP-seq. Tag counts in the left strand are shown as blue bars, tag counts in the right strand, as red bars. The unmappable locations are marked by grey blocks. The circles represent motif sites; the triangles, estimated sites. (a) 49% locations are unmappable. (b) 41% unmappable. (c) 38% unmappable.