Figure 3.
ATR-Chk1 pathway hypomorphic suppression is synthetic lethal with oncogenic Ras-transformation. A, Proliferation of H-rasG12V-transformed and control cells following ATR suppression. shRNA-mediated reduction of ATR was performed as described in Fig. 2. Cells were maintained at subconfluence by replating every two days, and cumulative population doublings were quantified over a total of 8 days. B, Western blot detection of ATR in lysates from control and H-rasG12V-transformed cells following shRNA-mediated ATR suppression (Day 2). C, Cell cycle profiles (PI staining) of control and H-rasG12V-transformed cells following ATR suppression. Sub-G1 populations are indicated (brackets). D, Quantification of average sub-G1 population frequency in H-rasG12V-transformed and control cells with or without ATR suppression. Data shown are derived from 3–6 independent experiments. For sections A and D, standard error bars are shown and P values were calculated by the Student’s t test.