(A) Western blots, (B) proliferation assays, (C, D) plate clonogenic assays, and (E, F) soft-agar assays on the engineered SUM159 and HCC1806 cells with 0.5 μg/ml Dox-induced overexpression of MAPK4 (iMAPK4) or control (iCtrl). The cells were also engineered with stable knockdown of PDK1 (shPDK1-1, shPDK1-2) or control (NT). Quantification data as means ± SD. Scale bar: 500 μm. P values by two-way ANOVA followed by Sidak’s multiple comparisons. *P ≤ 0.05, ***P ≤ 0.001, ****P ≤ 0.0001. Data are representative of at least 3 independent experiments. The numerical values underlying the figures can be found in S1 Data. MAPK4, mitogen-activated protein kinase 4; PDK1, phosphoinositide-dependent kinase-1.