Fig. 2
Decreased drug tolerance due to adenylate kinase 4 (AK4) knockdown in HeLa cells. a Left panel: western immunoblotting showing AK4 knockdown in cells expressing AK4 short hairpin (sh)RNA. AK4, 25 kDa; phosphorylated 5΄ AMP-activated protein kinase (p-AMPK), 64 kDa; β-actin, 42 kDa. Right panel: band densities were quantified using Image Lab (BioRad) and normalized to the internal control, alpha-tubulin *P < 0.05, **P < 0.01. b proliferation curves for AK4 shRNA cells and control shRNA cells, evaluated by xCELLigence (Real Time Cell Analysis System). Cells were evaluated after seeding at 5000 cells/well. The data are shown as mean ± standard deviation (SD) Cell Index (CI) values. c Cell numbers were counted 3 days after seeding under normoxic and hypoxic (1 % O2) conditions *P < 0.05, **P < 0.01. d Evaluation of drug sensitivity after AK4 knockdown showing the half maximal inhibitory concentration (IC50) for cis-diamminedichloro-platinum(II) (CDDP) and doxorubicin. IC50 values were determined by MTS assays. **P < 0.01. e Images of tumors resulting from HeLa cells grafted subcutaneously in nude mice on day 40 after grafting. f Graph showing the volume of HeLa cell grafts in nude mice at the indicated time-points. The data are shown as mean tumor volume (cm3) ± SD, **P < 0.01. g Western blotting analysis of HeLa cells 3 days after siRNA treatment. AK4, VDAC, Bax, or Bcl2 were detected at 25 kDa, 39 kDa, 21 kDa, or 26 kDa, respectively