Cytochrome c, which leaks from the mitochondrial intermembrane space into the cytosol, causes oligomerization of apoptotic protease-activating factor 1 (Apaf-1), forming a caspase activation complex known as the apoptosome. NS3694 is a cell-permeable diarylurea compound that inhibits apoptosome formation and caspase activation. It blocks cytochrome c-induced caspase activation in HeLa cell cytosolic extracts with an IC50 value of approximately 50 μM. NS3694 prevents the formation of apoptosomes, which prevents the association of procaspases with Apaf-1. It suppresses caspase activation and apoptosis in cells treated with either TNF-α or staurosporine . NS3694 is used to examine the role of apoptosome-mediated caspase activation in cell death.
