Figure 5.

PPI induces apoptosis via the activation of death receptor pathway. HepG2 cells were treated with PPI (2.5 μM) for 0, 1, 3, 6, and 12 h. Total RNA was extracted and synthesized into cDNA, and reverse transcription-quantitative polymerase chain reaction was conducted (a). HepG2 cells were incubated with PPI (2.5 μM) for 0, 3, 6, 12, and 24 h, and the key proteins of the death receptor signaling pathway were examined by western blotting analysis (b). The experiments were repeated three times. The results were presented as the mean ± standard deviation. ^∗p < 0.05 and ^∗∗p < 0.01, vs. the control group (0 h). PPI, polyphyllin I.