Proficiency of G2 DNA damage checkpoint in hCdc14A^Δ/Δneo or hCdc14B^Δ/Δ cells. (A and B) Cells were treated for 6 (hTERT-RPE) or 4 h (HCT116) with Noco with or without prior IR. Fixed cells were stained with PI and pH3 (n = 3; MI of irradiated cells normalized to corresponding unirradiated cells). (C, top) Cdc14A^flox/+ and Cdc14A^Δ/Δneo cells were treated with thymidine for 24 h and released for 7 h to reach G2 followed by treatment with or without DXR for 1 h. At the indicated times after release, cells were fixed and stained with PI and pH3. Flow cytometry is shown (n = 3). (bottom) Synchrony in G2 at time of DXR treatment. (D, top) Cdc14B^flox/flox and Cdc14B^Δ/Δ cells were synchronized in G1/S by double-thymidine block and released for 7 h and then as in C (n = 3). (bottom) Synchrony in G2 at the time of DXR treatment. (E, top) Cdc14A^flox/+ and Cdc14A^Δ/Δneo cells were treated as in C, harvested, and analyzed by IB. (bottom) Levels of Cdk1(Y15ph) induction quantified as in Fig. 1 F. Anti-Cdk1 signals used for the normalization. (F, top) Cdc14B^flox/flox and Cdc14B^Δ/Δ cells as in D. (bottom) Levels of Cdk1(Y15ph) as in E. Error bars indicate mean ± SD.