BCL2 and cancer: Next, we will discuss the antitumor activity of indole alkaloids in cancer in terms of apoptosis-related signaling pathways and targets, and the essential pathways and targets of apoptosis include death receptors and their ligands, Bcl-2 family, cytochrome c (Cyt-C), p53, nuclear factor kappa-B (NF-κB) pathway, phosphatidylinositol 3 kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) pathway, mitogen-activated protein kinase (MAPK) pathway, and so on.