Characteristics of DNase-seq 10-bp periodicity pattern. (A) Distances between reads from two different cell types (human umbilical vein endothelial cell line [HUVEC] and GM12878 lymphoblastoid cell line [LCL]) are plotted and show the 10-bp periodic spacing preference. We show lines both displaying distances from HUVEC reads to LCL reads and vice versa. (B) Similar read spacing plots showing 10-bp period is present in combined data from multiple cell types in DNase-seq data but absent in FAIRE-seq (Formaldehyde-Assisted Identification of Regulatory Elements) or permuted DNase data. (C) Read spacing plot showing 10-bp period in LCL DNase-seq reads overlapping non-LCL DNase I hypersensitive (DHS) sites but not in LCL-specific DHS sites.