Figure 4: CK2 knockdown induces cell apoptosis yet does not regulate EGFR-TKI resistance in PC9 and PC9/gef cells.

(a) Western blot analysis of CK2 alpha and beta subunit expression in PC9 and PC9/gef cells. (b) Western blot analysis of the efficiency of CK2α knockdown in PC9, PC9/gef and BEAS-2B cells. (c) Histogram of the cell survival rate (%) after knockdown using control shRNA, shLacZ and shCK2α (mean ± SE in triplicate experiments). (d) Cytotoxicity assays for various concentrations of gefitinib in CK2α-knockdown PC9 and PC9/gef cells.