This study analyzed nucleosome organization and chromatin accessibility at regulatory elements in differentiated cell types like macrophages. The researchers found that the macrophage master regulator Pu.1 maintains nucleosome depletion at regulatory regions. They also found that the chromatin remodeler Brg1 colocalizes with Pu.1, suggesting it plays an active role in organizing chromatin accessibility. Additionally, the histone variant H2A.Z was found to be highly associated with regulatory regions and Pu.1 sites in macrophages, and its binding is affected by inflammatory stimulus. Genome-wide maps of DNA accessibility were also generated.