Figure 2.

Effect of checkpoint protein depletion on phosphorylation events induced by primed M13 ssDNA. (A) Buffer, M13 + primer, or EcoRI-digested pBS (0.2 μg/mL) was added to mock-depleted or ATRIP-depleted NPE, and samples were analyzed as in Figure 1B. (B–E) NPE was mock-depleted or depleted with antibodies to RPA70 (B), TopBP1 (C), Rad1 (D), or Claspin (E). Mock-depleted NPE or depleted NPE was then incubated with M13 + primer, and samples were analyzed as in Figure 1B. Chk1 (B,C,E) and RPA (D) levels were monitored as loading controls. The lower band in E represents cross-reacting residual IgG in the extract from depletion.