FIG. 6.

Disruption of SCF^Skp2-dependent Cdt1 degradation does not generate DNA damage. (A) HeLa cells were transfected with an empty vector or vectors encoding wild-type (wt) Cdt1; Cdt1 Q3A, V6A, F9A, and F10A (ΔPIP); or Cdt1 T29A. Checkpoint activation was examined in these cells 2 days after transfection by immunoblotting. (B) HeLa cells were transfected with control, DDB1, or Skp2 siRNA oligonucleotides. Three days after transfection cell lysates were harvested and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and checkpoint activation was monitored by immunoblotting with the indicated antibodies.