Dhx9 is a genetic suppressor of ABT-737 sensitivity. (A) A pooled synthetic lethal shRNA screen in Myc-driven lymphomas depicting changes in representation of 813 informative shRNAs during 10 days of culture. shRNA depletion was calculated as the relative abundance in vehicle (dimethylsulfoxide)-treated cells divided by the relative abundance in ABT-737–treated cells. Values are plotted as the average of triplicate values in descending order. The dotted line represents 3 standard deviations from the population mean. Parenthesis denotes control shRNA pool location. (B) Percentage of GFP-positive Arf^−/−Eμ-myc/Bcl-2 lymphoma cells cultured in the presence or absence of 600 nM ABT-737 for 8 days after transduction with MLS constructs expressing the indicated shRNAs. Error bars are standard error of the mean; n = 3. (C) Western blot form whole cell lysates of Arf^−/−Eμ-myc/Bcl-2 lymphomas infected with the indicated shRNAs. (D) Viability of Arf^−/−Eμ-myc/Bcl-2 cells expressing the indicated shRNAs. The fraction of PI-negative cells was determined 16 hours after exposure to increasing concentrations of ABT-737 and set relative to vehicle-treated cells. Error bars are standard error of the mean; n = 3. (E) Scatter plot comparing the Dhx9 knockdown to ABT-737 sensitivity (R² = 0.66; P = .025; calculated using a paired Student t test).