Caspase-9 is an important enzyme that plays a key role in the process of programmed cell death, known as apoptosis. It is part of a family of proteins called caspases, which are responsible for executing the death program in cells. Caspase-9 is activated in response to various cellular signals, particularly those related to stress or damage, and it helps to initiate a cascade of events that lead to cell death. This enzyme is primarily activated in the intrinsic pathway of apoptosis, which is triggered by internal signals, such as DNA damage. Once activated, Caspase-9 can cleave and activate other caspases, amplifying the apoptotic signal and ensuring the orderly dismantling of the cell. Its proper function is crucial for maintaining cellular health and preventing diseases, including cancer.