In vivo, DNaseI chromatin accessibility maps now integrated into the Biophysical Browser chromatin accessibility maps from ENCODE are now integrated into the Biophysical Browser. Any of the ENCODE DNaseI data for a particular tissue type can be loaded in the Browser as an affinity-based positional prior that models DNA accessibility. Importantly, these affinity-based positional priors can be included in all the protein-DNA occupancy calculations – which greatly reduces false positive binding predictions in regions of inaccessible DNA.