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. 2011 Dec 15;6(12):e28862. doi: 10.1371/journal.pone.0028862

Figure 1. 5-FU and FdUrd activate the ATR and ATM checkpoint signaling pathways.

Figure 1

(A) Metabolism of 5-FU and FdUrd. (B, C) HT29 (B) and HCT-8 (C) cells were treated with 5-FU (80 µM, HT29 cells; 200 µM HCT-8 cells), FdUrd (40 µM for both cell lines), or 10 mM hydroxyurea (HU) for the indicated times. Cell extracts were blotted for phospho-Ser317-Chk1 (P-Chk1), phospho-Thr68-Chk2 (P-Chk2), Chk1, or Chk2. TS, thymidylate synthase; TP, thymidine phosphorylase; UP, uridine phosphorylase; UK, uridine kinase; OPRT, orotate phosphoribosyltransferase; RR, ribonucleotide reductase; FUR, 5-fluorouridine; FUMP, 5-fluorouridine monophosphate; FUDP, 5-fluorouridine diphosphate; FUTP, 5-fluorouridine triphosphate; FdUMP, 5-fluorodeoxyuridine monophosphate; FdUDP, 5-fluorodeoxyuridine diphosphate; FdUTP, 5-fluorodeoxyuridine triphosphate.