Quantitative analysis of polycomb response elements (PREs) at identical genomic locations distinguishes contributions of PRE sequence and genomic environment

This analysis showed that different PREs have quantifiably different properties, and that changes in as few as four base pairs have profound effects on PRE function, thus illustrating the power and sensitivity of ΦC31 site-specific integration as a tool for the rapid and quantitative dissection of elements of PRE design.