An RNA lacking the DSE is not able to form RNA-protein complexes under more stringent incubation conditions.

<p><b>Panel A:</b> Scheme of the RNA probes and competitors used in Panel B. Panel B: RNA-EMSA experiment using complete HeLa nuclear extract and the RNA probes of Panel A. The different radioactive RNA probes were incubated with 2 µg of HeLa nuclear extract and 15 µg/µl of heparin to generate more stringent incubation conditions. The experiment was performed in more stringent conditions (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058879#s2" target="_blank">Materials and Methods</a> section for details) than those used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058879#pone-0058879-g005" target="_blank">Figure 5</a> to make more evident the differences in complex formation efficiency.