Differential regulation of Cdt1 in response to the topoisomerase inhibitors Doxorubicin and Etoposide.

<p>HeLa and HepG2 cells were treated for 6 h with (A) Doxorubicin (0.2, 2 and 10 µM) (Doxo) or (B) Etoposide (20 and 80 µM) (Etopo), in the presence or absence of the proteasome inhibitor MG-132 (+MG-132). Total protein extracts were prepared and subjected to western blot analysis using antibodies against Cdt1, PARP, Geminin and Tubulin. (C) HeLa and HepG2 cells were synchronized in M phase with nocodazole, and subsequently were incubated with Etoposide (20 and 80 µM) (lanes 2–3, 7–8) or Doxorubicin (0.2 and 2 µM) (lanes 4–5, 9–10). Protein extracts were subjected to Western blot analysis using antibodies against Cdt1 and Tubulin.