Effect of exogenous PHB on STS-induced caspase-3 cleavage and apoptosis. Undifferentiated (A) and differentiated (B) granulosa cells were infected with adenoviral-PHB (MOI = 40, adenoviral-lacZ as control) for 24 h and then cultured with STS (1 μM, 2 h). The contents of cleaved, intact caspase-3 and PHB were examined by Western blot and the apoptosis rate of granulosa cells were assessed by nuclear morphology (Hoechst staining). Data are presented as mean ± SEM of three independent experiments and analyzed by two-way ANOVA and subsequently by Bonferroni post hoc test. **, p < 0.01 (compared with LacZ). NS: not significant.