Cell cycle events are regulated by the sequential activation and deactivation of cyclin depended kinase (Cdks) and by the proteolysis of cyclins. The cell division cycle (Cdc) genes are required at various points in the cell cycle. Cdc6 is the human homolog of Saccharomyces cerevisiae Cdc6, which is involved in the initiation of DNA replication. Cdc6 is essential for assembling the pre-replicative complex that forms at origins of DNA replication in the G1 phase of the cell cycle in budding yeast (S. cerevisiae). Cdc6 is also involved in checkpoint controls that ensure that DNA replication is completed before initiation of mitosis.