IH-induced cell death was associated PARP-mediated calpain activation. A: Immunostaining for calpain1 in RA4, IH4 and IH4 treated with 3AB groups. B: Quantitative assessment of immunostaining data from figure 4A. C: Western blot analysis of PARP and calpain was performed in the RA4, IH4 and IH4 treated with 3AB groups. β-actin was used as an internal control. **p < 0.01 for comparing each group with IH4day group by Dunnett's test in ANOVA.