Cellular activity of enhancer blocker activity. (A) Reporter scheme consisting of HBG1 promoter (GGlo) driving Puro and GFP expression. A CTCF site is interposed between the promoter and an HS2 enhancer to act as an enhancer blocker. (ITR) Sleeping Beauty inverted terminal repeats; (HS2) beta-globin hypersensitive site 2 enhancer. (B) Reporter plasmids cotransfected with a plasmid expressing the Sleeping Beauty SB100X transposase for random genomic integration. GFP activity was measured by flow cytometry. A1 and C1 represent previously characterized CTCF-binding insulator elements (Liu et al. 2015). A1Core and C1Core were truncated to the core 54-bp CTCF recognition sequence. FW and RV indicate forward or reverse orientation of insulator elements. Independent transfections are shown separately. Dots indicate median GFP levels, and whiskers extend to the 25th and 75th percentiles.
