MAPK4 and cancer: To further define whether MAPK4-induced PDK1 (MAPK4-PDK1 axis) plays any remarkable roles in promoting cancer cell growth, especially when combined with AKT activation, we investigated how co-expression of MAPK4D254A (with activation of MAPK4-PDK1 axis) and a constitutively activated AKT1 (AKT1T308D/S473D, AKT1-DD, to simulate MAPK4-AKT axis) affects SUM159 and HCC1806 cell growth.