a Combination index (CI) calculation for CP-673451 and GSK-650394 treatment in MDA-MB-231 (left) and BT-549 cells (right). b Colony-formation assays of MDA-MB-231 (left) and BT-549 (right) cells treated with DMSO or CP-673451 (2 μM) with increasing concentrations of GSK-650394. c MDA-MB-231 (left) and BT-549 (right) cells were treated with DMSO or CP-673451 for 1 h or a combination of CP-673451 (2 μM) and increasing doses of GSK-650394 for 5 days. Changes in p-AKT, total AKT, SGK1, p-NDRG1, and NDRG1 protein levels were analyzed by western blot. GAPDH served as a loading control. d Photographs of harvested tumors and quantification of MDA-MB-231 (left) and BT-549 (right) tumor-bearing mice treated with vehicle, GSK-650394 (150 µg/day, 5 days/week, subcutaneous administration), CP-673451 (50 mg/kg/day, 5 days/week, intraperitoneal administration), or a combination of both agents. Data are presented as the mean ± SD.