Synergy between Dhx9 suppression and ABT-737 is p53 dependent. (A) Arf^−/−Eμ-myc/Bcl-2 or p53^−/−Eμ-myc/Bcl-2 lymphomas were infected with MLS constructs expressing the indicated shRNAs and cultured in the presence of media containing vehicle or ABT-737, and the percent GFP⁺ cells was determined over an 8-day period. Error bars represent ± standard error of the mean; n = 4. (B) Immunoblot of cell extracts prepared from U2OS cells that had been infected with lentiviral constructs expressing the indicated shRNAs and harvested 3 days after infection. The ratio of shRNA abundance in the dimethylsulfoxide control-treated lymphomas was set relative to ABT-737–treated samples. (C) U2OS cells were infected with lentiviruses expressing the indicated shRNAs, and the percent GFP⁺ cell population after 2 days of culture in the presence of vehicle or ABT-737 was determined. The ratio of shRNA abundance in the dimethylsulfoxide control-treated lymphomas was set relative to ABT-737–treated samples. Error bars represent standard error of the mean; n = 2. (D) Competition assays were performed as in panel C except using U2OS cells that had been previously transduced with a lentivirus expressing p53.975. Error bars represent mean ± standard error of the mean; n = 3. (E) Immunoblot of extracts prepared from U2OS cells infected with lentivirus expressing the indicated shRNAs and harvested 4 days after infection.