Analysis of DNA content in L. major promastigotes after reversible arrest with HU. Cells obtained from 12 h-arrest with 5 mM HU (time 0) were harvested and incubated in fresh media in presence or absence of 5 μM CPT. After the time periods indicated, cells were stained with propidium iodide (PI) and analyzed by flow-cytometry. The graphs represent the relative PI fluorescence plotted against the frequency of events per channel. Each plot represents data collected from 20,000 events/sample.