**2.2 Cell viability**

Cell viability was evaluated by the method of Mosmann (1983) using 3-(4,5-dimethyl-2 thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT).

#### **2.3 Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay**

MH7A cells were fixed with 4% paraformaldehyde. After inactivating endogenous peroxidase with methanol containing 0.3% H2O2, a Permeabilization Buffer (Takara Bio Inc., Otsu, Japan) was applied to cells and stood on ice for 5 min. Then, a Labeling Reaction Mixture (Takara Bio Inc.) was added and incubated in a humidified chamber at 37°C for 60 min. Reactive cells were stained with 3% methyl green and detected with a light microscope.
