Skip to main content
. 2010 Nov 22;120(12):4453–4465. doi: 10.1172/JCI42240

Figure 2. Analysis of barrier insulator function in a position-effect variegation/gene silencing assay.

Figure 2

The indicated constructs were cotransfected into K562 cells with a pRSV-neo selection plasmid. Individual clones were isolated and expanded in G418-containing medium and switched to nonselective medium before analysis of GFP expression by FACS. GFP expression was reassessed at 3, 12, and 16 weeks. The number of GFP-expressing (GFP+) clones at 16 weeks and the total number of clones analyzed are shown. HS2, HS2 from the β-globin gene locus control region; EGFP, the coding sequence for the enhanced GFP gene; cHS4, HS4 from the chicken β-globin cluster; WT 5′HS Ank, a fragment containing the ankyrin 5′HS region; M GATA, the ankyrin 5′HS region with a mutation of the GATA1 site that abolished ankyrin promoter activity in vitro; 4X WT 5′HS Ank, 4 copies of the ankyrin 5′HS region; 108/153 5′HS Ank, the ankyrin 5′HS region with the –108 and –153 mutations.