The effect of phosphorylation or dephosphorylation on the CPT sensitivity of TopI activity in extracts from FACS separated CD44+ cells or CD44− Caco2 cells.

<p>(<b>A</b>) The TopI activity in CD44+ cell extracts after phosphorylation or dephosphorylation. Whole cell extract was either left untreated (indicated by Control) or incubated with phosphatase (indicated by Dephos) or CK2 (indicated by Phos) before TopI activity was measured by REEAD in the presence of 60 µM CPT or 5% DMSO as indicated in the figure. One example randomly picked out of 12 individual microscopic images of each reaction sample is shown in the top panel. A quantitative depiction of three independent experiments, obtained as described in the legend of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099628#pone-0099628-g001" target="_blank">figure 1</a> is shown in the lower panel. (<b>B</b>) Same as (<b>A</b>), except that the analyses were performed on extracts from CD44− cells.