MEK4 knockdown increases sensitivity to prednisolone. Western blot for MEK4 in the control NT cell line and in the shRNA-expressing Reh (A, top) or RS4;11 cell line (B, top). NT and MEK4-targeting shRNA Reh (A) and RS4;11 cells (B) were treated with increasing concentrations of prednisolone (middle) or doxorubicin (bottom) for 24 hours. Cell viability was measured by CellTiter-Glo assay. *P ≤ .05. NT, non(mammalian)-targeting shRNA.