(A) Immunoblots to examine the effects of shRNAs against ATR, ATM, and DNA-PKcs. Cells were collected at 84 hrs after the first shRNA infection. (B) Effects of shRNAs against ATR, ATM, and DNA-PKcs on the TIF response. Cells were collected 84 hrs after the first shRNA infection, for the last 6 hrs, cells were incubated either in the presence or absence of Shld1 and processed for IF-FISH as in Fig. 1. (C) Quantification of the TIF response measured as in panel B. Average TIF response values and SDs for shRNAs against ATR, ATM, and TopBP1 (sh2, see (D)) were derived from three independent experiments. A similar reduction in TIF response was observed with TobBP1 sh4 and sh5. (D) Immunoblot showing reduction in TopBP1 level in shRNA treated cells. See Suppl. Fig. 2 for related data.