c-TAK1 (Cdc25C associated protein kinase) phosphorylates Cdc25C on Ser 216 and is ubiquitously expressed in various human tissue and cell lines. C-TAK1 is distinct from Chk1, which also phosphorylates Cdc25C on Ser 216 in response to DNA damage. Phosphorylation of Cdc25C allows for the preferential binding of 14-3-3 proteins, subsequently retaining Cdc25C in the cytoplasm. Thus, the binding of 14-3-3 proteins prevents Cdc25C from dephosphorylating Cdc2 in the nucleus, thereby controlling the entry of the cells into mitosis. It is suggested that C-TAK1 mediates the binding of the 14-3-3 proteins through its kinase activity and acts as a negative regulator of mitosis.