Chromatin insulators separate active transcriptional domains and block the spread of heterochromatin in the genome. Studies on the chicken hypersensitive site-4 (cHS4) element. a prototypic insulator. have identified CTCF and USF-1/2 motifs in the proximal 250 bp of cHS4. https://mabelandfoxs.shop/product-category/kaleidoscope/