Vertebrate cells genetically deficient for Cdc14A or Cdc14B retain DNA damage checkpoint proficiency but are impaired in DNA repair

A recent study suggested that human Cdc14B phosphatase has a central function in the G2 DNA damage checkpoint. In this study, we show that chicken DT40, human HCT116, and human telomerase reverse transcription-immortalized retinal pigment epithelial cells deleted for the Cdc14A or Cdc14B gene are DNA damage checkpoint proficient and arrest efficiently in G2 in response to irradiation. Cdc14A knockout ( KO) or Cdc14B-KO cells also maintain normal levels of Chk1 and Chk2 activation after irradiation. Surprisingly, however, irradiation-induced gamma-H2A.X foci and DNA double-strand breaks persist longer in Cdc14A-KO or Cdc14B-KO cells than controls, suggesting that Cdc14 phosphatases are required for efficient DNA repair.