WP1130 induces apoptosis through activation of the intrinsic mitochondria-mediated pathway synergistically with BH3 mimetics. (A) HEL cells were left untreated as control (Cont.) or treated with 3 μM WP1130 (WP) for 20 h. Cells were analyzed for activated Bak and Bax by flow cytometry. (B) HEL cells were left untreated as control or treated with 3 μM WP1130 for 24 h. Cells were analyzed for the mitochondrial membrane potential (Δφm) by flow cytometry using DiOC6. Percentages of cells with reduced Δφm are indicated. (C,D) HEL cells were left untreated as control or treated for 24 h with 3 μM WP1130 with or without 100 μM Boc-d-fmk (BdF), as indicated. Cells were analyzed for activation of Bax (C) or DNA content (D) by flow cytometry. Percentages of apoptotic cells with the sub-G1 DNA content are indicated. (E) HEL cells transduced with wild-type (WT) Bcl-xL or its mutants (mt-1 or mt-8) as well as vector control cells (Cont.) were treated with indicated concentrations of WP1130 for 24 h and subjected to immunoblot analysis. C-Casp-3: cleaved Caspase 3. An arrow indicates the putative degradation product of Mcl-1. (F) Cells indicated were treated with 3 μM WP1130 for 20 h and analyzed. (G) HEL cells were left untreated as control or treated for 24 h with 1 μM ABT-737, 0.5 μM navitoclax, 10 μM A-1210477, or 1μM ruxolitinib with or without 2 μM WP1130, as indicated, and analyzed. (H) HEL cells were left untreated as control or treated for 6 h with 1 μM ABT-737 or 1 μM navitoclax with or without 5 μM WP1130, as indicated, and analyzed. (I) HEL cells were left untreated as control or treated for 6 h with 1 μM ABT-737 or 3.5 μM WP1130, as indicated, and analyzed.