In human cancer cell lines, re-replication induced by Cdt1 overexpression or Cdt1/Cdc6 co-overexpression occurs in early replicating regions of the euchromatin [11], whereas genome-wide studies in both S. cerevisiae and S. pombe have shown that re-initiating origins of replication are distributed throughout the genome with increased re-replication at subtelomeric sequences [17]–[19]. This evidence concerns the gene CDT1 and cancer.