Requirement of MAR for HSR generation.

<p>A. To examine the effect of the AR1 MAR sequence of the vector plasmid, we removed it and constructed three new plasmids, pTV-Rep-P∆AR1, pTV-MCS∆AR1, and pG5∆AR1. We transfected plasmids with or without the AR1 MAR into COLO 320DM cells, selected transfectants, and analyzed them by FISH. Frequency of HSR is plotted in the graph. B–D. The IR sequences from ß-globin Rep-P (B), c-myc (C), and <i>DHFR</i> (D) were analyzed using MAR-Wiz program, and the results (blue graph area) are shown. In each graph, regions with HSR-generation activity revealed by our previous study (<i>DHFR</i> and c-myc; [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077350#B18" target="_blank">18</a>]) and this study (ß-globin) are shown as gray rectangle(s). AT-rich and AG-rich tracts are also indicated.