DNase-seq is a powerful technique used to study the accessibility of chromatin in the genome. It involves treating cells with DNase I, an enzyme that digests DNA in regions where the chromatin is open and accessible. This allows researchers to identify active regulatory elements, such as promoters and enhancers, which play crucial roles in gene expression. After digestion, the remaining DNA fragments are sequenced to create a map of accessible regions across the genome. The resulting data helps scientists understand how gene regulation works and can provide insights into various biological processes and diseases, including cancer.