Fig. 1.
From: In vivo studies of the Drosophila insulator factor CTCF reach a Catch 22
The Abd-B gene and its associated 3’ regulatory region (not drawn to scale) cover 165 kilobases of DNA. See text for explanation. Wild type (WT) (a) and Fab-7 1 (b) embryonic nerve cords stained with antibodies against Abd-B have been dissected out. Abdominal segments are numbered A5, A6, A7. Panel (a) shows the presence of CTCF binding sites at Mcp, Fab-6, Fab-8 and at the Abd-B promoter. The 5’-3’ polarity of the Abd-B transcription unit is indicated