 In order to study the H4 acetylations in re-replicating origins, the investigators need to know which of cellular origins undergo re-replication in E1A cells in late S phase. the investigators are planning to identify the origins activated in E1A cells including those that re-replicate. Once the investigators identify one or two re-replicating origins, the investigators will quantify the acetylations using these origins in cells expressing epitope tagged WT and mutant HBO1 alleles and E1A. the investigators anticipate qualitative or quantitative or both in H4 acetylations due to E1A. 