Nuclear localization of GSK3β promotes resistance to standard AML chemotherapeutics. (A) The indicated cells with or without targeted GSK3β induction were treated with various doses of daunorubicin for 24 hours, and cell viability was determined by trypan blue staining (n = 2, HL60-NLS; n = 4, HL60-Cyto). (B) HL60-NLS cells were treated with tetracycline and 200 nM daunorubicin or 25 nM cytarabine for 2 days. The cell viability was assessed by Hoescht staining (n = 3; *P < .05, **P < .01). (C) The indicated cells with or without targeted GSK3β induction were treated with daunorubicin (200 nM) for 18 hours and analyzed by western blot for PARP or caspase 3 cleavage. (D) The indicated cells with or without targeted GSK3β induction were treated with daunorubicin for 2 days. Daunorubicin was washed away, the cells were plated in semisolid media, and colony formation was assessed after 7 days (n = 2). (E) Tetracycline-induced (0.2 µg/mL) and noninduced HL60-NLS cells were injected IV into NSG mice. Mice receiving tetracycline-induced cells were provided tetracycline-supplemented water (100 µg/mL). Four days post–cell injection, mice were injected with 1.5 mg/kg daunorubicin once a day for 3 days and monitored for survival (n = 5).