The Scheme (IMAGE) Lomonosov Moscow State University Caption A process of cell senescence is set in the early S-phase, when a topoisomerase-I collides a replication fork and a double-strand break appears. Credit Sergey Razin (NAR paper) Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.