The possible signaling mechanisms involved in the extract-induced apoptosis of A549 cancer cells were determined by western blotting analysis of standard apoptosis-related proteins, including pro-caspase 3, cleaved-caspase 3, pro-caspase 8, cleaved-caspase 8, pro-caspase 9, cleaved-caspase 9, Bcl-2, Bax, and cytochrome C. As shown in Figure 8A,B, the triterpenes of GLK (7.5, 15 and 30 μg/mL) decreased significantly the expression of the antiapoptotic protein Bcl-2 and pro-caspase 9 in a concentration-dependent manner. The gene discussed is CYCS; the disease is cancer.