Figure 6: D-limonene inhibits H2O2-induced caspase-3 and caspase-9 activation and modulates the expression of Bcl-2 family proteins in HLECs. The cells were pretreated with 500 and 1000 μM D-limonene for 12 h and then exposed to 100 μM H2O2 for 24 h. (a) The protein expression levels of Bax, Bcl-2, caspase-3, and caspase-9 were analyzed by western blot analysis; quantitative analysis was performed by measuring intensity relative to the untreated control. (b) The real-time PCR analysis of the apoptosis factors is shown. (c) The Bcl-2/Bax ratio was assessed. Each value represents the mean ± SEM for three independent experiments. , .