The role of Bim in apoptosis induced by ABT-199 and panobinostat, alone or in combination, in AML cell lines. (A and B) THP-1 (A) and U937 (B) cells were infected with non-target control (NTC) or Bim shRNA lentivirus particles overnight, then washed and incubated for 48 h prior to adding puromycin to the culture medium. The cells were then treated with ABT-199 and panobinostat, alone or in combination, for 24 h. Whole cell lysates were subjected to Western blotting. The fold changes for the Bim densitometry measurements, normalized to β-actin and then compared to no drug treatment control, are indicated. (C and D) THP-1/NTC, THP-1/Bim (C), U937/NTC and U937/Bim (D) cells were treated with ABT-199 and panobinostat, alone or in combination, for 24 h and then subjected to annexin V/PI staining and flow cytometry analyses. **indicates P<0.01 and ***indicates P<0.001.