Knockdown of TLE levels inhibits the apoptosis and cell death induced by AML1-ETO expression in U937T-A/E cells. U937T-A/E cells were infected with lentivirus containing a control shRNA (TLE4scr3), an shRNA directed against both TLE1 and TLE4 (TLE1/4si2, TLE1/4si3), an shRNA specific for TLE1 (TLE1si1) or TLE4 (TLE4si2), or an shRNA against other del9q CDR genes: FRMD3, GKAP1, SLC28A3, KIF27, C9orf103, C9orf64, RMI1, and HNRPK. (A) Four days after infection, expression of del(9q) CDR genes was evaluated by quantitative RT-PCR or Western blot in the case of HNRPK and are shown relative to the level of expression of each gene after infection with a control shRNA. To evaluate the specificity of TLE knockdown with TLE shRNAs, the expression levels of both TLE1 (■) and TLE4 (□) were measured. (B). After 2 days of infection, tetracycline was withdrawn and AML1-ETO was inducted. Cells were cultured an additional 6 days and then stained with annexin-V and 7-AAD to detect cells undergoing early apoptosis (annexin-V positive, 7-AAD negative) or dead cells in late apoptosis (annexin-V positive, 7-AAD positive). Three independent experiments were performed, and results for percentage of cells undergoing early apoptosis (■) and total apoptotic and dead cells (□) are summarized and expressed as the mean plus or minus SEM.