Fixed with 100 ethanol, treated with RNase A (50 mg/ml) for 15 min, and stained with propidium iodide (PI) (50 mg/ml). The fluorescence intensity was analyzed with FACSCalibur and CellQuest software (BD Biosciences, San Jose, CA, USA).Caspase activityCells treated with ZOL (Novartis Pharmaceuticals, Tokyo, Japan) were tested for the activity of caspase-3/7, -8 or -9 with respective Caspase-Glo kits (Promega, Madison, WI, USA). The relative activity level was calculated based on luminescence intensity of cells without any treatments.Materials and Methods Cells and miceHuman mesothelioma MSTO-211H cells were purchased from American Type Culture Collection (Manassas, VA, USA) and inhibitor EHMES-10 cells were kindly provided by Dr. Hamada (Ehime Univ., Ehime, Japan) [13]. Expressions of p14ARF and p16INK4A were negative and the p53 status was wild-type in both cells. BALB/c nu/nu mice (6-week-old females) were purchased from Japan SLC (Hamamatsu, Japan).Western blot analysisCell lysate was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then transferred to a nitrocellulose membrane, which was further hybridized with antibody (Ab) against p53 (Thermo Fisher Scientific, Fremont, CA, USA), phosphorylated p53 at serine (Ser) residue 15 (Cell Signaling, Danvers, MA, USA), unprenylated Rap1A (Santa Cruz Biotechnology, Santa Cruz, CA, USA) or actin (Sigma-Aldrich, St Louis, MO, USA) as a control, followed by an appropriate second Ab. The membranes were developed with the ECL system (GE Healthcare, Buckinghamshire, UK).Adenoviruses (Ad) preparationReplication-incompetent type 5 Ad expressing the wild-type p53 gene (Ad-p53) or the b-galactosidase gene (Ad-LacZ), in which the cytomegalovirus promoter activated transcription of the transgene, were prepared with an Adeno-X expression vector system (Takara, Shiga, Japan). The amounts of Ad were expressed as viral particles (vp).RNA interferenceCells were transfected with small interfering RNA (siRNA) duplex targeting p53 or with non-coding siRNA as a control (Invitrogen, Carlsbad, CA, USA) for 24 h using Lipofectamine RNAiMAX according to the manufacturer’s protocol (Invitrogen).Cell viability testCell viabilities were assessed with a WST reagent (Dojindo, Kumamoto, Japan) by detecting the amounts of formazan produced with absorbance at 450 nm (WST assay). The relative 
viability was calculated based on the 
absorbance without any treatments. Half maximal inhibitory concentration (IC50) and combination index (CI) values at the fraction affected (Fa) which showed relative suppression levels of cell viability were calculated with CalcuSyn software (Biosoft, Cambridge, UK). Fa = 1 and Fa = 0 indicate 0 and 100 viability assayed with the WST Table 1. Cell cycle distribution of ZOL-treated cells.Animal experimentsMSTO-211H cells were injected into the pleural cavity of BALB/c nu/nu mice. ZOL (25 mg) or the same amount of phosphate-buffered saline (PBS) was administrated intrapleurally on day 3, and CDDP (Bristol-Myers Squibb, New York, USA) (100 mg) or the same amount of PBS was injected Autophagy intraperitoneally on day 5. In this animal model, tumors became visible on day 9. The mice were sacrificed on day 24 and the tumor weights wereCell cycle distribution ( ?SE) ZOL (Concentration) (-) (-) (-) 10 mM 10 mM 10 mM 50 mM 50 mM 50 mM Time 24 h 48 h 72 h 24 h 48 h 72 h 24 h 48 h 72 h Sub-G1 1.0060.08 2.6660.10 6.8360.15 2.1260.10 4.7560.13 18.8460.12 2.0160.16 26.9860.76 79.1460.32 G0/G1 54.8360.4.Fixed with 100 ethanol, treated with RNase A (50 mg/ml) for 15 min, and stained with propidium iodide (PI) (50 mg/ml). The fluorescence intensity was analyzed with FACSCalibur and CellQuest software (BD Biosciences, San Jose, CA, USA).Caspase activityCells treated with ZOL (Novartis Pharmaceuticals, Tokyo, Japan) were tested for the activity of caspase-3/7, -8 or -9 with respective Caspase-Glo kits (Promega, Madison, WI, USA). The relative activity level was calculated based on luminescence intensity of cells without any treatments.Materials and Methods Cells and miceHuman mesothelioma MSTO-211H cells were purchased from American Type Culture Collection (Manassas, VA, USA) and EHMES-10 cells were kindly provided by Dr. Hamada (Ehime Univ., Ehime, Japan) [13]. Expressions of p14ARF and p16INK4A were negative and the p53 status was wild-type in both cells. BALB/c nu/nu mice (6-week-old females) were purchased from Japan SLC (Hamamatsu, Japan).Western blot analysisCell lysate was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then transferred to a nitrocellulose membrane, which was further hybridized with antibody (Ab) against p53 (Thermo Fisher Scientific, Fremont, CA, USA), phosphorylated p53 at serine (Ser) residue 15 (Cell Signaling, Danvers, MA, USA), unprenylated Rap1A (Santa Cruz Biotechnology, Santa Cruz, CA, USA) or actin (Sigma-Aldrich, St Louis, MO, USA) as a control, followed by an appropriate second Ab. The membranes were developed with the ECL system (GE Healthcare, Buckinghamshire, UK).Adenoviruses (Ad) preparationReplication-incompetent type 5 Ad expressing the wild-type p53 gene (Ad-p53) or the b-galactosidase gene (Ad-LacZ), in which the cytomegalovirus promoter activated transcription of the transgene, were prepared with an Adeno-X expression vector system (Takara, Shiga, Japan). The amounts of Ad were expressed as viral particles (vp).RNA interferenceCells were transfected with small interfering RNA (siRNA) duplex targeting p53 or with non-coding siRNA as a control (Invitrogen, Carlsbad, CA, USA) for 24 h using Lipofectamine RNAiMAX according to the manufacturer’s protocol (Invitrogen).Cell viability testCell viabilities were assessed with a WST reagent (Dojindo, Kumamoto, Japan) by detecting the amounts of formazan produced with absorbance at 450 nm (WST assay). The relative viability was calculated based on the absorbance without any treatments. Half maximal inhibitory concentration (IC50) and combination index (CI) values at the fraction affected (Fa) which showed relative suppression levels of cell viability were calculated with CalcuSyn software (Biosoft, Cambridge, UK). Fa = 1 and Fa = 0 indicate 0 and 100 viability assayed with the WST Table 1. Cell cycle distribution of ZOL-treated cells.Animal experimentsMSTO-211H cells were injected into the pleural cavity of BALB/c nu/nu mice. ZOL (25 mg) or the same amount of phosphate-buffered saline (PBS) was administrated intrapleurally on day 3, and CDDP (Bristol-Myers Squibb, New York, USA) (100 mg) or the same amount of PBS was injected intraperitoneally on day 5. In this animal model, tumors became visible on day 9. The mice were sacrificed on day 24 and the tumor weights wereCell cycle distribution ( ?SE) ZOL (Concentration) (-) (-) (-) 10 mM 10 mM 10 mM 50 mM 50 mM 50 mM Time 24 h 48 h 72 h 24 h 48 h 72 h 24 h 48 h 72 h Sub-G1 1.0060.08 2.6660.10 6.8360.15 2.1260.10 4.7560.13 18.8460.12 2.0160.16 26.9860.76 79.1460.32 G0/G1 54.8360.4.